Eighteen clues contain deficient wordplay, the missing elements of which, when highlighted, confirm the theme.
 

Across

1 Party with a previously haughty man (6)
6 Waste disposal initially declined (7)
11 Small braces (4)
12 Dog has a drink outside well (5, 4)
13 Boozer hugging a member’s tree (5, 3)
14 Old coins from the Parisian musical (6)
15 Bloody fool’s excellent! (5)
16 Plant box Alison covers (6)
18 Cash error — not good (3)
20 Officer deserting error-free break in (6)
21 High-tension Bletchley Park unit (3, 3)
22 Paint a terribly venomous snake (6)
23 Fast-moving quiet echinoderm (8)
29 Add to layer (8)
32 Dullard beat a groin (6)
33 Piece of black grass (6)
37 Some pseudo-insane behaviour (6)
39 Chief from Western Gabon? (3)
40 Barrier on grey ground (6)
41 Previous boss of brother (5)
42 Even vacated den being discussed (2, 4)
43 Awfully inept, so hurry (4, 2, 2)
44 Ex-race guys so desperate outside WC (9)
45 Food in unopened charcuterie (4)
46 Scold boy about Tom (5, 2)
47 Old flame’s source changed assent (6)
 

Down

1 Bearskin worn by old south American assistants (7)
2 Canadian novelist Harold, off and on (6)
3 Norfolk town business, half into hoax (8)
4 When set like an operational jet? (6)
5 Good, rough, short Indian carts (7)
6 Run after dissolute scavenger (5)
7 Message about posh fool over gaffe (4, 3)
8 Chip circuits backed upthen left (5)
9 Judge raised note to enter property (8)
10 Sleeping son 37 stirred (7)
12 A king — his law (5, 2)
17 Matthias regularly loves Sneezy’s report? (7)
19 Virgin Mary’s bet about daughter (3, 4)
24 Tuber in gutter, rotting (5, 3)
25 Tests vacuous petitions — they’re thin (7)
26 Will’s resolved powerless grants (2, 6)
27 Navy finally signed off boats (7)
28 Press first sarcastic type (7)
30 Very old book size (7)
31 Orange article poor Jane’s buried (7)
34 Chance hospital annex is unfinished (6)
35 Musician is trapped by headless android (6)
36 See Russian girl’s flower there (5)
38 New way to save November, a month (5)

A first prize of £30 for the first correct solution opened on 17 August. There are two runners-up prizes of £20. Please note that until further notice entries should be clearly scanned or photographed and emailed (including just the crossword number in the subject field) to crosswords@spectator.co.uk — the dictionary prize will not be available. We will revert to postal entries post-pandemic. Please allow six weeks for prize delivery.