The unclued lights (five of two words, two pairs and a singleton) are of a kind, verifiable in Brewer.
 

Across

 
11    Ore obtained by worker underground, a trainee (7)
12    DJ due to broadcast around ten (6)
16    Bound by discretion, one is silent (5)
19    Quandary of back-cover girl (7)
21    Bridge closure? (4)
23    In France the one certain time for relaxation (7)
24    Second bird in winter nest (4)
25    Setter’s quick riposte around the end of June — does it get on your nerves? (7)
31    Crossing-point for number of French (4)
32    Treads that are relative (7, hyphened)
34   Top of robe that’s in fashion gets ripped (4)
35    In wraps, she should embrace summer in France (7)
37    Made a hole, say, in a piece of wood (5)
40    Welsh girl’s average, about third in English (5)
41    Norton’s characters who utilise libraries? (9)
42    Health of sportsmen having appeal (6)
43    Cooker, not new, slowing down on the whole (7)
44    Make-up list for Shrove Tuesday? (11, two words)
 

Down

 
1    Immodest Ben reviewed incorporations (11)
2    Oil spilt during wine fiddle (6)
3    Cancel yearly publication, after fifth has been shelved (5)
5    Monstrous figures regularly met in court case (4)
6    Enrich with alcohol in line with unbeatable service (4)
7    Faux pas having arrived during silent uprising (7)
8    Car Edward checked over (7)
9    Fantasies limit Liberal parties (9)
10    Tornado scrambled creating a stink (7)
20    A unit I’m forming in a single detail (7)
27    Launch site with low take-up period (7)
28    Country lane at the end more rocky, it’s said (7)
33    Almost noon, not late (6)
36    Put one’s foot down — it’s time to study (5)
38    Aussie PM has well under half popular vote (4)
39    This lad upsets another! (4)
 
A first prize of £30 for the first correct solution opened on 25 March. There are two runners-up prizes of £20. (UK solvers can choose to receive the latest edition of the Chambers dictionary instead of cash — ring the word ‘dictionary’.) Entries to: Crossword 2398, The Spectator, 22 Old Queen Street, London SW1H 9HP. Please allow six weeks for prize delivery.