2369: Prodigious

Each of ten clues contains a misprinted letter in the definition part. Corrections of misprints spell a word which can be read as an indicator of the unclued lights in each of four columns of the grid.
 

Across

 
1 Revolutionary avoids accepting one god (7)
6 Destroyed each bit of opium (7)
11 Priest and paramour lapsing? (6)
12 Tense champion catching alien in addition (7)
14 Mouldings attached to front of impressive gateway (5)
15 Dredge section mostly exposed (5)
16 See current process releasing a vitamin (6)
17 Rascal having problem carrying Albanian coin around (6)
19 Worn-out horse, mad at vet, I smarten up (9)
21 Chief among fish on rack (7)
24 Ten trials prepared for disinfectant (9)
26 Crustacean left in court put out (9)
29 Ponder, miles away, wrecked (7)
30 Cross with fiddle in list (9)
32 Parrot and fish for old emperor (6)
33 Hot contest in middle of battle, rash (6)
35 Want less density in soil (5)
36 Make up for deficiencies in area with shade (5)
37 Hurdy-gurdies in market back after struggle (7)
38 King in craft, injured, short of time (6)
39 What bothered rash author? (7)
40 Tip seen to work for sculptor (7)
 

Down

 
2 Dowdy juror typecast in part (5)
3 Declare past possessions (4)
4 Stalk to lie broken, covered by pipe (9)
6 New list in article on special plants (8)
7 Thefts shattered thesis (6)
9 Academician cheers plan, for instance, for towers (8)
13 Bare certainty about answer (8)
18 Principal notice in border with flower (10)
20 Paltry remedy around end of bout drunk (8)
22 Fellow with shiner is struggling to deliver knockout blows (9)
23 Canoe, concerning sailor, in end capsized (8)
28 Artist in spot showing spirit (6)
29 Liked energy in trick (6)
31 Cold on long hike (5)

A first prize of £30 for the first correct solution opened on 13 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 2369, The Spectator, 22 Old Queen Street, London SW1H 9HP. Please allow six weeks for prize delivery.