Across:
1 Blowing hot and cold (FICKLE) for hundred (-C-) thousand (-K-) found in queue (file = FI-LE) (FICKLE),
4 From my perspective (AS I SEE IT), a (A-) relative (-S I S-) on drugs (ecstasy = -E-) is to join (tie) up (= reverse indicator) (tie = -E IT)? (AS I SEE IT),
9 Unoriginal film (REMAKE) produced about (RE-) model (-MAKE) (REMAKE),
10 Is the plant’s supervisor perhaps (BOTANIST) into bats? (into bats) That’s batty! (= anagram indicator) (into bats = BOTANIST),
12 Opposed to (RESISTANT) block (RESIST-) on a (-A-) number of good books (New Testament = -NT) (RESISTANT),
13 Massive group (HORDE) from NATO left on the road (‘NATO’ left ‘on the road’ = herod = HORDE),
14 Nearly all of 21 across (nearly all ‘salts’ = SALT) and 3 down (lakes) briefly (s) (‘lakes’ without ‘s’ = LAKE) go to, for instance, West Jordan CITY) (SALT LAKE CITY) – the large conurbation that’s in Utah (SALT LAKE CITY),
18 Strong government (STATIS-) taking most of (k) the credit (tick) (‘tick’ without ‘k’ = -TIC-) for one (-I-) article (-AN) (STATISTICIAN) by one who can read figures (STATISTICIAN),
21 Preserves, in a way (SALTS), on ice coming off coastlines (‘on ice’ coming off ‘coastlines’ = astls = SALTS),
22 Cover costs (BREAK EVEN) as Brendan (Bren = BRE- -N) is over Anne, primarily (Anne primarily = -A-), as well as Kay (-K) and Eve (EVE-) (BREAK EVEN),
24 Made-up (= anagram indicator) tie clip (tie clip = E-PLICIT) containing cross (-X-) (EXPLICIT) – that’s crystal clear (EXPLICIT)
25 Gets carried away by love (ELOPER) on the run to a secret getaway? (ELOPER),
26 Take five (-REST-) in Tamworth (Tamworth pig = P-IG-) reaching finish line (finish ‘linE’ = -E) (PRESTIGE) with status that’s recognised by others (PRESTIGE),
27 Crowds out (USURPS) for United (U-) playing (= anagram indicator) Spurs (Spurs = -SURPS) (USURPS).
Down:
1 In favour of (FOR-) taking lock (lock/hair = -TRESS) (FORTRESS) from secure place (FORTRESS),
2 It’s a waterproof (Macintosh = mac) backing (= reverse indicator) (mac = CAM-) on one (-I-) unique (-SOLE) (CAMISOLE) article of clothing (CAMISOLE),
3 Superior (LAKE- Superior) to Old Bob (old bob/shilling = -S) (LAKES), Albert and Victoria, for instance (Lake Albert and Lake Victoria = LAKES),
5 One of those who knows the score (SPORTSCASTER) is wrestling and rowing (SPORTS-) with those playacting (-CAST-) in the hospital (-ER) (SPORTSCASTER),
6 A taste of Italy (SPAGHETTI) in Pat’s eight (Pat’s eight) ingredients (= anagram indicator) (Pat’s eight = SPAGHETTI),
7 Political exile (ÉMIGRÉ) offering regime (regime) change (= anagram indicator) (regime = ÉMIGRÉ),
8 Test pilot blows top (‘test pilot’ blows ‘top’ = estilt = TITLES) with a number of counts (a number of Counts = noble TITLES),
11 Bad mouthing (BACK-STABBING) rugby players (BACK-S-) from club (bat) flipping over (= reverse indicator) (bat = -TAB-) short (e) session (binge) (‘binge’ without ‘e’ = -BING) (BACK-STABBING),
15 Presumably you won’t get a lunch break with this dark, laborious type (LATE SHIFT) of work schedule? (LATE SHIFT),
16 Television (TV = -T V-) unit (-I-) consumed by musician (piper = PI- -PER) (PIT VIPER) – the one spitting venom at the snake charmer (PIT VIPER),
17 Catches (ENSNARES) Egyptian Nubian leaders (‘Egyptian Nubian’ leaders = EN-) unsettling (= anagram indicator) Nasser (Nasser = -SNARES) (ENSNARES),
19 Gone out for the night (ASLEEP) in this state after counting the sheep (ASLEEP),
20 Turns up (= reverse indicator), has a sixth sense (extrasensory perception = ESP = -PSE) to go on the drink (ale = ELA-) (ELAPSE) and pass the time of day? (ELAPSE),
23 Weekend (‘week’ end = K-) drinks (-ALES) (KALES) with The Greens (KALES).