Across:
1 Father (Rev) upset (= reversal indicator) (Rev = -VER-) in shady type (TA-N) (TAVERN) of bar (TAVERN),
4 Tries hot (tries hot) soup (= anagram indicator) (tries hot = THEORIST) produced by speculative type not known for their experimentation (THEORIST),
9 Gallery in the house (LOGGIA) locked up (= reverse indicator) by Padraig Goldsmith (locked up by ‘padrAIG GOLdsmith’ = aiggol = LOGGIA),
10 Don’t turn a blind eye (TAKE NOTE) to what reporter might do (TAKE NOTE),
12 Recalls (= reverse indicator) bird (grebe = -E-BERG) entertaining Pole (North Pole= -N-) and local Yank (tug = GUT-) (GUTENBERG), an old bookmaker (German printer who was the first to use a printing press = Johannes GUTENBERG),
13 Risky flipping call (call one makes when the referee flips coin = heads or tails = HEADS) from schoolteachers (HEADS),
14 A (A-) retweet (-RT) by past master (HISTORIAN) (ART HISTORIAN) – a crafty type who knows all about the old pictures (ART HISTORIAN),
18 14 across opens (‘art historian’ opens = ART) preserves (TREASURES) (ART TREASURES) valued by someone who knows their sunflowers (Van Gogh’s paintings of Sunflowers) from their water lilies, for instance (Claude Monet’s “Water Lilies”) (ART TREASURES),
21 Approve (ADOPT) area (A-) around (= reverse indicator) Hull (pod) (pod = -DOP-) close to the port (close ‘porT’ = -T) (ADOPT),
22 Lounge (LIE) has fashionable (IN) job for those talking orders (WAIT tables) (LIE IN WAIT) – it will require one to be patient before onslaught begins (LIE IN WAIT),
24 Put out of action (DISABLED) by deli’s bad (delis bad) organisation (= anagram indicator) (delis bad = DISABLED),
25 More cunning (WILIER) from women (W-) associated with fiction (-LIE-) in Iran (IR = -I-R) (WILIER),
26 Newish top (‘Newish’ top = N-) on (-ON-) pick-up (-SENSE) (NONSENSE) is rubbish (NONSENSE),
27 Busy (HECTIC) architect gets rid of art (‘architect’ gets rid of ‘art’ = chiect = HECTIC).
Down:
1 Vehicle (T-RAM) carrying The Spanish ('the' Spanish = -EL-), for example (e.g. = -EG-) (TELEGRAM), in The Wire (TELEGRAM),
2 Do nothing (VEGETATE) for The Greens (VEG-) taking direction (East = -E-) from world power (state) with no leader (s) (‘state’ without ‘s’ = -TATE) (VEGETATE),
3 Rule (REIGN) from base off Bering Sea (‘base’ off ‘Bering Sea’ = ering = REIGN),
5 Most of those in 13 across (most of ‘heads’ = HEAD), 19 down (‘garden’ = GARDEN-) and in hospital (-ER) (HEAD GARDENER) with Adam, presumably (HEAD GARDENER),
6 Picks up (OVERHEARS) that man (-HE-) and initially (‘And’ initially = -A-) kept a hold of playing (= anagram indicator) Rovers (Rovers = OVER-RS) (OVERHEARS),
7 Lads falling off sailboards (‘lads’ falling off ‘sailboards’ = siboar = ISOBAR) – it could be the pressure staying on a line (ISOBAR),
8 Takes cues from sheet music (takes ‘cues’ from ‘sheet music’ = hetmsi = THEISM) and belief in the creator (THEISM),
11 Driver’s aid (golf TEE-) is complete (-TOTAL-) cobblers (cobblers) for a fair amount (half of) (half of ‘cobbLERS’ = -LERS) (TEETOTALLERS) of those who never drink alcohol and drive, for instance (TEETOTALLERS),
15 Prickly (IRRITABLE) Blairite (Blairite) angry (= anagram indicator) (Blairite = IR-ITABLE) about first Referendum (first ‘Referendum’ = -R-) (IRRITABLE),
16 Paper (ORGAN-) provides the basic idea (gist): “Missing Leader (g) (‘gist’ without ‘g’ = -IST) (ORGANIST) is Playing in The Church” (ORGANIST),
17 Recites (recites) novel (= anagram indicator) (recites = ES-TERIC) about love (-O-) (ESOTERIC) – stuff that’s puzzling to most (ESOTERIC),
19 Has a soft spot for The Greens (GARDEN) and that’s a growing concern (GARDEN),
20 Neuroscientist has no interest (‘neuroscientist’ has no ‘interest’ = uocnis = COUSIN) in relative (COUSIN),
23 Inched away from Indo-Chinese (‘inched’ away from ‘Indo-Chinese’ = oinse = NOISE) racket (NOISE).