Island

[ MAJOR(significant/important) + A(abbrev. for “area”) ] containing ( bordering ) “C”(pronounced/we hear, the same as “sea”) . — Fifteensquared

Press

“irony”(saying things that you don’t really mean) minus its last letter ( endlessly … ). — Fifteensquared

such philosophy?

Last letter of ( Ultimately ) “ Aquinas ” plus ( and ) anagram of ( … disseminated ) CATHOLICS . — Fifteensquared

president once

“wills”(decrees/specific instructions) minus its middle letter ( Heartless … ) plus ( by ) ON(working). — Fifteensquared

not changed

[ 1st letter of ( …’s first ) “ Everton ” and “ Derby “] contained in ( … clothes ) UNITED(as used in the names of teams, like Manchester United). — Fifteensquared

drinks

BRO(short for “brother”, a relative) + WALES(part of/somewhere in the UK) containing ( swallows ) N(in maths, symbol for an indefinite number). — Fifteensquared

old civilisation

Container

AY (synonym="a poetic form of “always”") in MAN (synonym="a piece on a chess board, in this case/say, the bishop") = MAYAN; definition: "old civilisation"

pork pie

S(abbrev. for “son”) plus ( given ) (T OR Y)[either the front end or back end of “tasty”). — Fifteensquared

Birds

WILDE(Oscar, the Irish wit) containing ( circling ) [ G(abbrev. for “good”) + reversal of ( … to the west , in an across clue) SEE(to spot/to look). — Fifteensquared

capital port

[L(abbrev. for “large”) + SINK(to drop/come to a lower level)] contained in ( drunk by ) [ HE(that guy) + I(Roman numeral for “one”) ]. — Fifteensquared

country

SN(abbrev. for “south” and “north” poles) contained in ( Keeping … apart … ) [WED(joined in matrimony) + E(abbrev. for “European”) ]. — Fifteensquared

Patience,

[ I + COPE(to manage/to deal with effectively)] contained in ( to keep in ) [ CO(abbrev. for “company”) plus ( getting ) anagram of ( … twisted ) ARM . — Fifteensquared

eg 1st of December, 2nd of May, 6th of August, 4th of June

1st letter of ( 1st of ) “ December ” + 2nd letter of ( 2nd of ) “ May ” + 6th letter of ( 6th of ) “ August ” + 4th letter of ( 4th of ) “ June “. — Fifteensquared

formal attire

[OP(abbrev. for “opus”, a literary or musical work) + H(abbrev. for “hard”) ] contained in ( in ) reversal of ( … to return ) STAT(short for “statistic”/a fact). — Fifteensquared

Release

“untrue”(mendacious/lying) minus its last letter ( a lot of … ) SS(Schutzstaffel, the fascist organisation of the Nazi Party. — Fifteensquared

showing more endurance

“harrier”(a cross-country runner) with “d”(abbrev. for “day”) replacing ( has … for ) “r”(abbrev. for “run” in cricket scores). — Fifteensquared

Channel

SINS(goes wrong/commits an immoral act) containing ( about ) U(one of the ratings in the classification system of film). — Fifteensquared

praise

ANNA(Pavlova, famed ballerina) placed below ( with … topping , in a down clue) [ H(abbrev. for “hot”) plus ( getting ) OS(abbrev. for “outsize”/huge) ]. — Fifteensquared

Oblivious to the world,

Reversal

AS (synonym="like/having similar characteristics") + PEEL (reversal="once British Prime Minister") = ASLEEP; definition: "Oblivious to the world,"

home

Reversal of ( … climbing , in a down clue) “boy”(child) minus its last letter ( mostly ) + STATE(to say/to declare) ] containing ( around ) IN(at home, as in “I’m home if you want to visit”). — Fifteensquared

fantasy

C(abbrev. for “caught” in cricket scores) + HIM(that chap) + reversal of ( … to bring up , in a down clue) RE(about/with reference to) + A(abbrev. for “adult”). — Fifteensquared

One cannot stand

Anagram

anagram of AD (synonym="abbrev. for “advertisement”, of which a bill/poster is an example") + HIDEOUS (synonym="… drunk") + DIVE (synonym="DIVE") = AHOUSEDIVIDED; definition: "One cannot stand"

Logodaedalus, say

[ 1st and last letters of ( Extremely ) “ devious ” + reversal of ( …’s rising ) I’M(setter is/I am, with the setter using the self-referential pronoun)] contained in ( in ) WORTH(value/merit). — Fifteensquared

Italian who drew

Charade

TIE (synonym="a game/sports match between individuals or teams in a knock-out competition") + POLO (synonym="a game/sport played on horseback") = TIEPOLO; definition: "Italian who drew"

Pooh-pooh

Anagram

anagram of SAID (synonym="bust") + DIN (synonym="a noise, an example of which/perhaps is Boom!") = DISDAIN; definition: "Pooh-pooh"

Covers

S(abbrev. for “special”) + HEAT(an English entertainment magazine/a celeb mag) + reversal of ( … in a spin ) SH!(keep mum/quiet). — Fifteensquared

Like hikers

ON(taking, as in “are you on medication?”) + F(abbrev. for “fellow”) + reversal of ( … towards the top , in a down clue) TOO(as well/also). — Fifteensquared

down supplier

Charade, Reversal

RE (synonym of "Engineers") + DIE (synonym of "fail") [reversal: "to"]; definition: "down supplier"