2452: Comme on dit

The unclued lights (five of two words and one of three) should be paired to reveal four expressions verifiable in Brewer. Ignore one accent.

Across

10 Plant setter left, it being covered in resin (5)
11 Hardy bay tree? Obviously not (6)
12 Bioethical problem of 150 willing to participate with 18 (7)
16 Central American distributed narcotics – a fool (10, two words)
17 Be subject to stress pointlessly (8)
20 Purple stonecrop – otherwise almost rosé, in France (5)
21 The very nature of German city church (7)
22 Queen Elizabeth and Prince Philip have no love for old coins (5)
24 Several parishes with services starting mid-week (3)
27/18 Positive evidence of porcine acupuncture? (6)
31 Toss last bit of pepper into casserole (5)
33 Not starting daily exercise? It’s this! (7)
34 Bird and Australian shellfish on bow of trawler (5)
35 One old party remains backing cones (8)
38 Some hammer Ephesians regularly (4)
40 Derrick or Redgrave, we hear – sturdy Scots (6)
41 Roman soldier is a great distance away! (5)
42 Tattered ends I’d twisted – proven (14, three words)

Down

2 Small clumsy fellow is a boor (4)
3 Halt dinner getting cooked in region away from a port (10)

4 Oil from the Cotswolds? (7)
5 The cream of the Carmelites (5)
7 Preparing for winter drive, taking risk going over bottom of avenue  (7, hyphened)
8 Svelte, small gnome gets extremely drunk, we’re told (14, hyphened)
9 It’s more than enough having quiet time to fast at end of May (6)
13 Bishop, for example, with quarters in ecclesiastical residence (5)
15 Farm leader deposed from local office (5)
18 See 27 Across
19 Foyers, where 37 blue ones get scattered (10)
23 Trembled, when in small fragments (8)
26 Marmoset from the west is a small monkey (7)
28 Love pleasant place for topping – it’s waiting in readiness (5, two words)
29 Small flat’s ready (3)
30 Sack on French bed, glittering in the flames (7)
35 Woman even outside displays radiance (5)
37 Eve stripping displays underwear (4)

A first prize of £30 for the first correct solution opened on 27 April.