Across:
1 Deciding never again to go down wrong path (GOING STRAIGHT) as the crow flies (GOING STRAIGHT),
10 Took issue with (OPPOSED) old (O-) port (-P-) – it doesn’t look natural (-POSED) (OPPOSED),
11 Half the book (half the‘VOLume’ = VOL-) by staff (cane) isn’t finished (e) (‘cane’ without ‘e’ = -CAN-) to order (-O) (VOLCANO) – one is bound to blow one’s top (VOLCANO),
12 A basic requirement (NEED) of ne’er-do-well dismissing Orwell (‘neer do well’ dismissing ‘Orwell’ = need = NEED),
13 Steel (steel) bust (= anagram indicator) (‘steel’ = ‘STELE’) from concrete memorial (gravestone = STELE or stela),
15 One of the big cats (LION) from Africa not found in California (‘Africa’ not found in ‘California’ = loni = LION),
17 Put away (EAT) or defended by defence attorney (defended by ‘defencE ATtorney’ = EAT),
19 All that remains (FOSSIL) of a type of aluminium material (aluminium foil = FO- IL) wrapped around ship (-SS-) (FOSSIL),
21 Private (SECRET) school (S-) on Crete (Crete) redevelopment (= anagram indicator) (Crete =-ECRET) (SECRET),
22 Something for those crying out (TISSUES) for car (model T-) for lots of children (-ISSUES) (TISSUES),
23 Unnerve someone (RATTLE) on the ramparts of Rathangan Castle (on the ramparts of ‘RAThangan CasTLE’ = RATTLE),
25 A measure of the appropriate speed (TIMING) of container (tin = TI-N-) going over motorway (-MI-) is key (music key -G) (TIMING),
27 Roar from War Room: (‘roar’ from ‘war room’ = wom = MOW) “Cut them down on the field” (MOW),
29 Takes what isn’t theirs (ROBS) up (= reversal indicator) in Hillsborough (hillSBORough = sbor = ROBS),
30 Natalie (Natalie) withdraws, that is (i.e. = ie) (‘natalie’ withdraws ‘ie’ = NATAL), to return to the point of delivery (place/time of one’s birth = NATAL),
31 Some macho bohemian (some ‘macHO BOhemian’ = HOBO) produced Drifter (HOBO),
34 Not all (t) the gear (‘kit’ without ‘t’ = KI-) and cocaine (-C-) found in the palace (-KING) (KICKING) is giving one a hit to boot? (KICKING),
35 Stately home (MANSION) or pile abandoned in Minneapolis (‘pile’ abandoned in ‘Minneapolis’ = minnaos = MANSION),
36 Cracking up (GOING TO PIECES) on the way out (GOING) keeping tabs on leaders (‘Tabs On’ leaders = TO), kings and queens, for instance (PIECES on chessboard) (GOING TO PIECES).
Down:
2 Exotic (= anagram indicator) posers (posers = OP-RESS) going around park (-P-) (OPPRESS) trample under feet (OPPRESS),
3 Rejected (= reversal indicator) in its entirety (‘iTS ENtirety’ = tsen = NEST) – it’s for the birds (NEST),
4 Teased (teased = SEDATE) criminal (= anagram indicator) with dope (SEDATE),
5 Sweetheart (lover) reverses (= reversal indicator) (lover = REVOL-) car (model T = -T) (REVOLT) in disgust (REVOLT),
6 Policed without cop (‘policed’ without ‘cop’ = lied = IDLE) – the type that’s not working (IDLE),
7 I’ve (ive) moved (= anagram indicator) (ive = -VIE-) in here (‘here’ = ‘hear’ = HEA-R), by the sound of it (= homophone indicator) (HEAVIER), and the lift is more difficult to operate (HEAVIER),
8 Risking everything (GOING FOR BROKE) getting word from auctioneer (GOING, going gone) in favour of (FOR) getting smashed (BROKE) (GOING FOR BROKE),
9 Heading for Croke Park (GOING TO GROUND) for hiding? (GOING TO GROUND),
14 Sounds like something within range (EARSHOT) to share (to share) out (= anagram indicator) (to share = EARSHOT),
16 Tag (TITLE) of posts from test pilots (‘posts’ from ‘test pilots’ = tetil = TITLE),
18 Labour (= anagram indicator) tries (tries = RESIT) to have a look at The Paper again (RESIT),
20 Whopper (LIE) served up (= reversal indicator) in Marseilles (in ‘marsEILles’ = eil = LIE),
21 Place (SET) belonging to Siamese twins (belonging to ‘SiameSE Twins’ = SET),
24 Heartless (b) abbot (‘abBot’ without ‘b’ = abot) knocks back (= reversal indicator) (abot = TOBA-) first course (first ‘Course’ = -C-) with cold (-C-) duck (-O) (TOBACCO) and leaves for a smoke (TOBACCO leaves for smoke/cigarette),
26 Stand in awe of (IDOLISE) one (I-) party (-DO-) demolishing (= anagram indicator) lies (lies = -LISE) (IDOLISE),
27 Serves up (= reversal indicator) starters from the old garden (starters from ‘The Old Garden’ = tog = -GOT) and endless (e) venison (game), for instance (‘game’ without ‘e’ = gam = MAG-) (MAGGOT), for grub (MAGGOT),
28 Prepare to play (WARM-UP) in the heat? (WARM-UP),
32 Stop (‘stop’ SIGN) veteran from Evening Star (‘veteran’ from ‘evening star’ = nigs = SIGN),
33 Joint (KNEE) discovered rolled up (= reversal indicator) in Aberdeen kilt (in ‘aberdEEN Kilt’ = eenk = KNEE).