ACROSS
1 Unruffled church leader wearing tartan cloth (6)
PLACID – C[hurch] in PLAID; easy when you see it
4 Stocky bumpkins in first part of trashy film (8)
THICKSET – HICKS in T[rashy] ET
10 Estimated cost of passage from St Paul, perhaps? (9)
QUOTATION – I think the idea here is that a part of the Bible when cited can be called a quotation, but I am open to offers
11 More senior lord received by English queen (5)
ELDER – LD in E ER
12 Aquatic amphibian moved away, missing lake (3)
EFT – [l]EFT for the useful Scrabble word
13 Glaring politician’s photo initially unwanted round America (11)
CONSPICUOUS – CONS PIC U[nwanted] O (round) US
14 A way teachers recalled a cold, treeless zone (6)
TUNDRA – reversal of A RD NUT (National Union of Teachers)
16 Replacement of kidney involving theatre crew ultimately (7)
RENEWAL – [theatr]E [cre]W in RENAL (of kidney)
19 Apt to forget made-up names one coined originally (7)
AMNESIC – anagram* of NAMES I C[oined]; describes me well in my 60th year
20 I work in turfy ground, finding woodlouse, for example (6)
ISOPOD – I + OP in SOD (turfy ground)
22 Courier given keys by member of guild (11)
DELIVERYMAN – D E (random musical keys) LIVERYMAN
25 Signal agreement? Homer sometimes did (3)
NOD – ‘Even Homer nods’ is a proverb meaning that even the best sometimes makes a mistake due to a momentary lapse
26 Complaint from queen, perhaps, brought back without purpose? (5)
MIAOW – reversal of W/O (without) AIM (purpose)
27 Dimwit’s problem a boy soldier reversed (9)
IGNORAMUS – reversal of SUM A RON GI
28 Young bird in web disturbed by small fish (8)
NESTLING – S (small) in (‘disturbed by’) NET (web) LING (fish)
29 Huggy type not entirely happy — tho nearly (6)
PYTHON – hidden in [hap]PY THO N[early]; I was looking for something meaning touchy-feely, but this is not a creature you would want embracing you. Up to 5 metres long in parts of Asia, I believe.
DOWN
1 Card-game in Paris that’s eclipsed by mine (6)
PIQUET – QUE (French for ‘that’) in PIT
2 Change of tack with regard to revolution (5-4)
ABOUT-TURN – ABOUT TURN; the crypticity level is not too high in this one
3 Man using current account to cover appeal (5)
ISAAC – SA ([sex] appeal) in I (current) AC (account)
5 Suspended Irishman in father’s toothless legislature? (4,10)
HUNG PARLIAMENT – HUNG LIAM (Irishman) in PARENT
6 Time to leave street party — it’s getting noisier! (9)
CRESCENDO – CRESCEN[t] DO
7 Social misfit theologian introduced to Portuguese saint (5)
SADDO – DD in SAO (Portuguese for ‘saint’ as in Sao PAolo)
8 Employing son for second time, strangle singer (8)
THROSTLE – THROTTLE with S for the second of the three Ts for the bird
9 Quiet agreement at home about old instrument (5,9)
PIANO ACCORDION – PIANO (quiet) ACCORD O (old) in IN (at home) for the instrument famously played by James Stewart in Night Passage. Director Anthony Mann, who had made a number of films with Stewart including westerns The Naked Spur and The Man from Laramie, didn’t see eye to eye with Stewart about these musical interludes (Stewart was a keen amateur player, but not good enough to save him from being dubbed by a pro for the final cut), so by the time Mann came round to directing perhaps his finest western (and arguably the greatest of all time – Man of the West) it was an ageing and ailing Gary Cooper who got the lead.
15 Repudiation doctor said I for example talked of? (9)
DISAVOWAL – SAID* sounds like VOWEL
17 Forest-dweller with sex appeal eclipsing dandy regularly (4,5)
WOOD NYMPH – D[a]N[d]Y in W (with) OOMPH
18 Musician and detective on island propping up bar (8)
BANDSMAN – DS (detective) MAN (island) on BAN (bar)
21 Inventor displaying lack of arrogance when given rise (6)
EDISON – reversal of NO SIDE (arrogance)
23 Roles for top players City picked up (5)
LEADS – sounds like LEEDS
24 Anxious French marshal clutching version of Bible (5)
NERVY – RV (REvised Version) in [Marshal] NEY
Still don’t know who Marshal Ney was.