Across:
1 Some hijab Armani’s (some ‘hijab Armanis’ = BARMAN) selling to his local regulars (BARMAN),
4 One of those forgettable types (AMNESIAC) of academicians dropping acid (‘academicians’ dropping ‘acid’ = aemcians = AMNESIAC),
9 Consent to (ACCEDE to) AC/DC (ACDC = ACC-D-) touring (= anagram indicator) around Spain (-E-) with One Direction (east = -E) (ACCEDE),
10 It’s the epitome of elitism (SNOBBERY) finishing Pilgrimages (finishing ‘pilgrimages’ = S-) with Byron (Bryon = -NOB-RY) travelling (= anagram indicator) around Belgium (-BE-) (SNOBBERY),
12 Recognition (DISCOVERY) of what the scientist was hoping to make (DISCOVERY),
13 Get wind of the fact (LEARN) Tom is not in Montreal (‘Tom’ is not in ‘Montreal’= nreal = LEARN),
14 Picture (SELF-PORTRAIT) what only you are capable of, you poser (SELF-PORTRAIT),
18 What the politician stands for in The House (SEAT) bolsters (CUSHIONS) (SEAT CUSHIONS) those with soft spots for the backbenchers perhaps (SEAT CUSHIONS),
21 A French feminine type (French ‘a’ = une = UN-E) entertains 150 (Roman 150 = -CL-) (UNCLE) from the family (UNCLE),
22 Crude (OIL) torture (PAIN-) on backstreet (back/reverse street = St = -TS) (OIL PAINTS) used, for example, by one of those producing 14 across (OIL PAINTS used by someone producing ‘self-portrait),
24 Writer (pen) briefly (n) (‘pen’ without ‘n’ = -PE-) consumed by sci-fi (sci-fi = S-CIFI-) compilation from the start (‘compilation’ from the start = -C) (SPECIFIC) that’s explicit (SPECIFIC),
25 Manual (manual = ALUMNA) work (= anagram indicator) for female graduate (ALUMNA),
26 Allotted (ASSIGNED) leading actor (leading ‘actor’ = A-) from first Shrek (first ‘Shrek’ = -S-) and The Omen (-SIGN-) with English (-E-) director (-D) (ASSIGNED),
27 Yard (-Y) is behind (= positional indicator) police trap (STING-) (STINGY) – how mean is that? (STINGY).
Down:
1 Give it a violent shake (BRANDISH) for breakfast (BRAN-) and for lunch perhaps (-DISH) (BRANDISH),
2 Music (ROCK music) on the boat (SALT) (ROCK SALT) synonymous with The Cellar (ROCK SALT),
3 Sound (AUDIO) of car (AUDI-) taking roundabout (-O) (AUDIO),
5 Exchanged notes (exchanged notes/notes that are exchanged = MONEY) on square (T-) close to Russian capital (-ROUBLE) (MONEY TROUBLE) – one of those in the red knows all about it (MONEY TROUBLE),
6 Sell him (sell him = EM-LLISH) out (= anagram indicator) around Belgium (-BE-) (EMBELLISH) and exaggerate the story (EMBELLISH),
7 Second time (second ‘time’ = I-) Charlie (-C-) Lincoln (Abe Lincoln = -E BA-) upset (= reversal indicator) George (-G) (ICE BAG) getting the cold shoulder in the hospital (ICE BAG),
8 College (C-) is attempting (trying) to get rid of the head (t) (‘trying’ without ‘t’ = -RYING) (CRYING) – it’ll end in tears (CRYING),
11 Cops the mysterious type (SECRET POLICE) concealed (SECRET) by monitor (POLICE) (SECRET POLICE),
15 Pressure (P-) is not as intense as it was (-RECEDING) (PRECEDING) earlier (PRECEDING),
16 An issue for animal (YOUNG) worker (MAN) (YOUNG MAN) – the type that’s immature (YOUNG MAN),
17 One (I-) getting letters of distress (-SOS-) to stay (stay = -TASY) away (= anagram indicator) (ISOSTASY) interests the geologist, whose crust is in the balance (ISOSTASY),
19 Airs (airs = R-SIA) broadcast (= anagram indicator) around America (-US-) (RUSSIA) – the world’s largest country? (RUSSIA is the world’s largest country),
20 Barman (SC-) produces beers (brews) with no head (b) (‘brews’ without ‘b’ = -REWS) (SCREWS) for a number of twists (SCREWS),
23 Stonewall without news (‘stonewall’ without ‘news’ = toall = ALLOT) to distribute (ALLOT).