Across:
1 Darn it – (HECK-) the French (the = -LE) (HECKLE) give stand-up guy a hard time (HECKLE),
4 Raises my (raises my) problem (= anagram indicator) (raises my = EMISSARY) with The Messenger (EMISSARY),
9 Emotional (MOVING) film (movie) without energy (e) (‘movie’ without ‘e’ = MOVI-) is no good (No Good = -NG) (MOVING),
10 Sticks out (OBTRUDES) as do brutes (do brutes) all over the place (= anagram indicator) (do brutes = OBTRUDES),
12 Turns up (= reversal indicator), hideaway (lair = -RIAL) on top of (top ‘Of’ = -O-) Irish beach (Irish ‘beach’ = trá = -ART-) point (S-) (SARTORIAL) is tailored for the man of the cloth (SARTORIAL),
13 Ideal position (NICHE) for hotel (-H-) in Mediterranean city (NIC-E) (NICHE),
14 A French (a = UN-) teacher (principal) heard (= homophone indicator) (‘principal’ = ‘principle’ = -PRINCIPLE-) deputy head (‘Deputy’ head = -D) (UNPRINCIPLED) is lacking in integrity (UNPRINCIPLED),
18 Writing (from the 3Rs = R-) ain’t (-AIN- T-) about Bob (bob/curtsy = -BOW) on short (e) course (‘route’ without ‘e’ = -ROUT) (RAINBOW TROUT) with colourful swimmer (RAINBOW TROUT),
21 Get this from the bar (ROUND) for the swingers before the 19th hole presumably (ROUND of golf),
22 The first clue, as it is known (ONE ACROSS), is perfect (hone) starting off? (h) (‘hone’ without ‘h’ = ONE) Answer (A-) – it’s irritable! (-CROSS) (ONE ACROSS),
24 Fired (shot = SHO-T) over women (-W-) taking snake (-BOA-) (SHOWBOAT) to flashily put on an act (SHOWBOAT),
25 Neglected (= anagram indicator) a cough (a cough = GAUCHO) working on the plains in South America (South American cowboy = GAUCHO)
26 An expert on spelling perhaps (SORCERER), Clare (-CE-) is consumed by awful (= anagram indicator) errors (errors = SOR-RER) (SORCERER),
27 Likelihood (CHANCE) of having some rich ancestors (having some ‘riCH ANCEstors’ = CHANCE).
Down:
1 House (HOME-) band’s final (‘bandS’ final = -S-) music (punk) clip (k) (‘punk’ without ‘k’ = -PUN) (HOMESPUN) is plain, in the material sense (HOMESPUN),
2 They hide what’s really happening (COVER-UPS) with mugs (C-UPS) boxing – it’s no longer on (-OVER-) (COVER-UPS),
3 The locals say (LINGO) Mao came from Mongolia? (‘Mao’ came from ‘Mongolia’ = ngoli = LINGO),
5 Places to stay (MOBILE -S) around Ring (PHONE-) (MOBILE PHONES) – ideal for those who are expecting the call (MOBILE PHONES),
6 Most peculiar (STRANGEST) two streets (St + St = ST-ST) either side of Dutch house (House of Orange) needing no introduction (o) (‘Orange’ without ‘o’ = -RANGE-) (STRANGEST),
7 Point out (ADDUCE) in site (site) report (= homophone indicator) (‘site’ = ‘cite’ = ADDUCE),
8 Alarm (= anagram indicator) enemy (enemy = YE-MEN) incorporating endless (end ‘lesS’ = -S-) (YES-MEN) sycophants (YES-MEN),
11 Music venue (DISCO-) is not the first (‘Not’ the first = -N-) to broadcast (sow) mostly (w) (‘sow’ without ‘w’ = -SO-) behind schedule (-LATE) (DISCONSOLATE) or to be low in spirits (DISCONSOLATE),
15 Irish (I-)- Pole (North Pole = -N-) within hearing range (-AUDIBLE) (INAUDIBLE) is impossible to pick up (INAUDIBLE),
16 African (MOROCCAN) officer (Officer Commanding = -OC-) caught (-C-) in rebuilt (= anagram indicator) manor (manor = MOR-AN) (MOROCCAN),
17 Checks out The Hearing (OTOSCOPE) with old (O-) Count (count = tot) briefly (t) (‘tot’ without ‘t’ = -TO-) where there’s capacity (-SCOPE) (OTOSCOPE),
19 Conservative (C-) teacher (Sir) retires (= reversal indicator) (Sir = -RIS-) from institute (-I-) and school (-S) (CRISIS) in The Emergency (CRISIS),
20 A little birdy will tell you this (a little birdy tells you a RUMOUR) drink (RUM-) is like lemon juice (sour) with no head (s) (‘sour’ without ‘s’ = -OUR) (RUMOUR),
23 War of words (CLASH) lost (-L-) in capital (capital/money = C-ASH) (CLASH).