Across:
1 Condition (HEALTH) of Moor (moor/heath = HEA-TH) going around lost (-L-) (HEALTH),
4 Taking a swipe in court perhaps (serving ball in tennis court = S-ERVING) over women (-W-) (SWERVING) changing direction (SWERVING),
9 Ran away from Greenland (“ran” away from “Greenland” = geenld = LEGEND) in traditional story (LEGEND),
10 It (-IT-) upsets (= reversal indicator) soldier (GI = -IG-) in The Departed (L-ATE) (LITIGATE) to take action (LITIGATE),
12 Little deceptions (WHITE LIES) in acceptable levels of fiction (WHITE LIES),
13 Song and dance (SCENE) witnessed in the abbey (SCENE in The Abbey Theatre),
14 Invest in (INSTAL-) a manner of speaking (Latin = -LATI-N) around old (-O-) (INSTALLATION) art exhibit (INSTALLATION),
18 Travel agent perhaps (HOLIDAYMAKER) is taking a break (HOLIDAYMAKER),
21 Head over heels (= reversal indicator) with a (-A) sparkler (gem = -MEG-) on ring (O-) (OMEGA) produced by Greek character (OMEGA),
22 Good (G-) vintage (-OLD) from China (PLATE) (GOLD PLATE) from a precious film (GOLD PLATE = precious film/layer),
24 Similar to one of those in 23 down (“plane” = JET-) getting car (model -T-) from one (-I-) family member (-SON) (JETTISON) for scrap (JETTISON),
25 What one might take when taking leave (WAY OUT) is off the wall (WAY-OUT),
26 Pretend to be ill (MALINGER) to delay (-LINGER) graduate (MA-) at the start (= positional indicator) (MALINGER),
27 Military unit (DETAIL) in part destroyed ETA illegally (part “destroyed ETA illegally” = DETAIL).
Down:
1 Worthily (worthily = HOLY WRIT) translated (= anagram indicator), this sounds like a summons from the man upstairs (HOLY WRIT),
2 Most likely to get all steamed up (ANGRIEST) moving (= anagram indicator) inert gas (inert gas = ANGRIEST),
3 Strung out TENSE) giving the past, present and future action (verb forms = TENSE),
5 Takes order (WAITS AT TABLE) from Washington (Washington = WA-) – it’s (-ITS) a (A-) battle (battle = -T TABLE) plan (= anagram indicator) (WAITS AT TABLE),
6 One of the downsides of The Cloud (RAINSTORM) or that’s part of the forecast (RAINSTORM),
7 Ungodly types (IMAGES) of appalling (= anagram indicator) ageism (ageism = IMAGES),
8 Local chap (GEEZER) is great (G-) with domestic appliance (freezer) when father (Fr) leaves (“freezer” without “Fr” = -EEZER) (GEEZER),
11 Old Penny (old penny coin = D-) and Gillian (Gillian = -IALLING) Cook (= anagram indicator) find mood (TONE) (DIALLING TONE) indicative of the lineout (DIALLING TONE),
15 Calling (-VOCATION) centre of Philately (centre of “Philately” = A-) starting (= positional indicator) (AVOCATION) to collect stamps, for instance (hobby = AVOCATION),
16 Give the go-ahead (OK-) for the foreign (the = -LA-) unfinished (e) residence (“home” without ‘e’ = -HOM-) for the middleclass (middle “class” = -A) (OKLAHOMA) in America (OKLAHOMA),
17 Awkward (= anagram indicator) relation (relation = ORIENTAL) from the East (ORIENTAL),
19 Comes to a standstill (LOGJAM) with record (LOG-) to preserve (-JAM) (LOGJAM),
20 Learnt (learnt = RENTAL) scheme (= anagram indicator) could be a temporary solution for those on holiday (RENTAL),
23 Parking (P-) on narrow street (-LANE) (PLANE) on a flat surface (PLANE).