Unclued lights are of a kind, including one of two words, all listed in Chambers or Oxford (the required spelling of 12 across is given by both dictionaries). One clued light can be rearranged to form a possible two-word description of each unclued light and must be highlighted.

Across

1    A certain confusion with church garment (8, hyphened)
8    Went back exhibiting profundity (4)
16    Dancer’s perhaps losing one without right performers (9)
17    Lean meat, game from the east (7)
22    Native Americans nearly get lost (4)
23    Unknown German crew turning on sailor (7)
25    Cherry drink knocked back in hardship (6)
26    Covers of special registers (7)
28    Skunk fine after bit of a kip (4)
29    Break in France is by river (4)
34    Spiders raced through safe haven regularly (7)
35    A swim around in river, shaking (9)
37    Buyer to stop person on horse? (7, hyphened)
38    Musical missing a step no longer (5)
39    Crookedly earn item with scam, getting fines (12)
40    Spot in Hautes-Pyrénées (4)

Down

1    Good mathematician’s work period (6)
2    Number one could be number ten (4)
3    Ultimately, run and caper about? (6)
4    Give out unopened message lacking graces (7)
5    Doctor pried into edible plant, one producing juice (10, two words)
6    Dead or rotten cedar (6)
7    Wicked Satanic rune is not 27 (11)
8    Condemn 40, not 7 (5)
9    Attempt to throw dates and pear around (9)
10    Lacking inspiration for vessel (7)
13    Native Australian ruler to gloat (8, hyphened)
15    Wimp holding back is made European (11)
19    Family of plants came up, covering great area (8)
25    Man’s wrapping paper from island (7)
27    Decision by a learner lacking objectivity (7)
30    Workers joining, but not with church officials (6)
31    Article reduced panic for woman (6)
32    New Saint spilling tears around Spain (6)
33    Bubbly agent admitting hesitation (5)

A first prize of £30 for the first correct solution opened on 12 August. 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 2418, The Spectator, 22 Old Queen Street, London SW1H 9HP. Please allow six weeks for prize delivery.