In each of eight clues, one letter has been cut from the definition part; the cut letters spell a word that defines each of four unclued lights. In each of five clues, one letter has been added to the definition part; the added letters spell a word that defines each of four unclued lights. The words spelt by the cut and added letters, when linked by 17, form a doubly hyphened term whose definition in Chambers includes the puzzle’s title. One unclued light consists of two words.

Across

6 Purge resistance in mass after time (6)
12 Single nasty taunt hurt (10)
13 Cargo boats yielding medium gains (5)
14 Feat once seen — how stirring (7)
15 Cinnamon for instance in basic battered chest (10, hyphened)
16 Supply aid to restrict crime, all round (7)
22 Lamentation led by grandmother, loth (7)
23 Catches sailor in Nova Scotia (4)
24 Poet keeping involved with Norse god’s worshipper (7)
26 Governor in denial before demo? (7)
30 Nose formerly partly cut, I see (4)
34 Fear mostly of swing (4)
36 Old extravagance one among Tories abandoned (7)
38 Revise gags, wildly hostile (10)
39 Service by personality backing lotteries (7)
40 Soldier in clash for revenues (5)
41 Current treatment I endure, endlessly impractical (10)
42 House reduces jets (6)
43 Established opening covered by chairman with dignity (8)

Down

2 Golden rule in a broadcast broken by American (8)
3 Upset in arena puzzled governor (5)
4 Sunshade artist provided, held by friend (7)
5 Sneeze in middle of duties, surrounded by dust, over and over (7)
7 Fresh herb all right for antelope (6)
8 Love room in harem, up and about (5)
10 Police policy has ardent cops excited (13, two hyphens)
11 Punt still bearing east on stream, not north (9)
18 Revere ring without us (5)
19 Base suggestion on energy limit (9)
21 Rode fast, moving ahead of force (5)
27 Shut underground chapel, missing point (3)
29 Sectarian position, embracing upward way (7)
33 Loosens about fifty frames (6)
35 Drama involving golf ace on Muirfield’s third tee (5)
37 Palm court supporting elevated skill (5)

A first prize of £30 for the first correct solution opened on 4 January. 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 2240, The Spectator, 22 Old Queen Street, London SW1H 9HP. Please allow six weeks for prize delivery.