Across:
1 Hairstyle (MOHAWK) tips for marketing outfit (tips for ‘Marketing Outfit’ = MO-) to sell door to door (-HAWK) (MOHAWK),
4 Sounds like (= homophone indicator) Ryle (‘Ryle’ = ‘rile’ = OFFEND-) Ward (ward = -ER) (OFFENDER) is the culprit (OFFENDER),
9 Type of humour (DRY humour) on The Hill (tor = ROT) reflects (= reversal indicator) (DRY ROT) problem in some neck of the woods perhaps (DRY ROT),
10 Likely to work (FEASIBLE) with American (-A-) consumed by strange (= anagram indicator) beliefs (beliefs = FE-SIBLE) (FEASIBLE),
12 Old (O-) revolutionary (= reverse indicator) father (Rev = -VER-) – group (herd) on the radio (= homophone indicator) (‘herd’ = ‘heard’ = -HEARD) (OVERHEARD) picked up on (OVERHEARD),
13 Starter of chickpeas (starter of ‘Chickpeas’ = C-), honey (-LOVE) (CLOVE) and a little garlic (CLOVE),
14 Potential Irish windfall (SWEET WILLIAM apple) for darling (SWEET) Bill (WILLIAM) (SWEET WILLIAM),
18 Ceremony for prospective partners (CIVIL SERVICE marriage) in Government administration (CIVIL SERVICE),
21 Often the first thing out of characters’ mouths (HELLO) in The Inferno (HELL-) is to do with love (-O) (HELLO),
22 From The Theatre (OPERATION) to open-air (to open air = OPERATION) adaptation? (= anagram indicator),
24 Individual (ON-E-) covering fashion (fashion = -LOOK-) from centre of Paris (from centre of ‘paEis’ = -R) (ONLOOKER) for The Observer (ONLOOKER),
25 Spanish poet (Federico García Lorca = LOR-CA) wearing Iberian top (‘Iberian’ top = -I-) (LORICA) with old Roman corselet (LORICA),
26 Politician (TD = T-D) welcoming new (= anagram indicator) marina (marina = -AMARIN-) (TAMARIND) with an Asian Pod (TAMARIND),
27 Break a promise to (RENEGE) Rocky (= anagram indicator) Greene (Greene = RENEGE).
Down:
1 Rodent (mouse = M-OUSE) going around had (had = -ADH-) travelled (= anagram indicator) (MADHOUSE) from residence synonymous with the Tea Party (residence synonymous with the Mad Hatter’s Tea Party = MADHOUSE),
2 Dietary concern for Arabian? (for Arabian horse = HAY) Getting iron (FE-) on top of vitamins (on top of ‘Vitamins’ = -V-) in hospital (-ER) (HAY FEVER) for what’s an allergic reaction! (HAY FEVER),
3 Tune from Townhouse (‘tune’ from ‘townhouse’ = owhos = WOOSH) is the sound of Rush (WOOSH),
5 Pitch (FIELD) to 1000 (grand = G-) young women (-LASSES) (FIELD GLASSES) offering the long view (FIELD GLASSES),
6 It’s not difficult (it’s EASY) for the professor to get this (professor gets the CHAIR) (EASY CHAIR) – as for the rest? (EASY CHAIR),
7 One in the red (DEBTOR) oyster bed is missing? Yes! (‘oyster bed’ is missing ‘ yes’ = otrbed = DEBTOR),
8 The man in Ring (man in boxing ring = referee = RE-F-) keeps key (music key = -E-) that opens entrance rattling (opens ‘Entrance Rattling’ = -ER) (REEFER) in jacket (REEFER jacket),
11 What’s keeping the crafty types afloat off Australia (PACIFIC OCEAN) and around New Zealand? (PACIFIC OCEAN),
15 Typical French standard raised (French standard/flag = TRICOLOUR) in The Banner, at home (TRICOLOUR),
16 Opening 18 across (opening ‘civil service’ = CIVIL-) for sage (wise) heading off (w) (‘wise’ without ‘w’ = -ISE) (CIVILISE) to socialise (CIVILISE),
17 Captivate again (RE-ENGAGE) with a fair amount of (half of) the omen (half of ‘omEN’ = -EN-) in reggae (reggae) medley (= anagram indicator) (reggae = RE-GAGE) (RE-ENGAGE),
19 We are not in hot water (‘we’ are not in ‘hot water’ = hotatr = THROAT) finding the frog there (THROAT),
20 No rush in small hours (no ‘rush’ in ‘small hours’ = smallo = SLALOM), of course, for those on the slippery slope (SLALOM),
23 Came around (AWOKE) to middle-class (middle ‘clAss’ =A-) taking Chinese pot (-WOK-) and drugs (-E) (AWOKE).