Nonsense by Craft

For nine symmetrically-placed entries, definitions in clues lead to an answer which must be treated before entry. Wordplay in those clues leads directly to the entry. Somewhat surprisingly, entries are real words.
A further four symmetrically-placed entries have normal clues, but must be treated twice before entry. Solvers might expect this to produce nonsense, but answer lengths are unaffected.
A single letter has been removed from all other down clues and must be replaced before solving.
In clue order, these give a cryptic description of the theme.

Across
1 Most flash underwear on command (8)
6 Eyes about to open, finally, welcoming in the morning (5)
10 Open out at regular intervals, but narrowly, along line (6)
11 People in power accepting fake coin for treatment (7)
12 Compound interest’s primary goal when talking about stocks (6)
14 One receiving cash and joint from radio host (5)
16 In retirement, Craft sells possessions in ancient woods? (8)
18 Good boy is civil in language and address (4)
20 Flash of enlightenment provided by analysing ratios (6)
21 Once again, lay sliced fruit between toasted rye (7)
23 Ass burdened by lightest metal in faint morning sunrise (6)
24 Fundamentally, ditzy overdressed lady labelled thus? (4)
26 Presents home of wizard in cave (5)
27 Start conflagration (4)
29 One originally just found in North America, near centre of reservation, at one end of Colorado? (6)
30 After firing seconds, squire set off more peacefully (7)
33 In support, steer revolutionary missile (6)
35 Bright sun to rise, making horizons invisible (4)
38 In Eurasia, produce Top Gear with international following (8)
40 Marble area before entrance (5)
41 One that ruminates on Twitter, following its owner (6)
42 Insect in barrel containing measure of cloth (7)
43 Bird pair with one offspring (6)
44 Arrogant Communists? (5)
45 Sopranist forgetting intro from Prodigy’s “twisted firestarter” (8)

Down
1 Townsman having strong desire in bedroom (6)
2 One piece of bread and a pie? (6)
3 “Length essential to long seat” is not complex (5)
4 Lamb had sickness when rearing, having end of nose amputated (4)
5 Depravity engulfing old singer (5)
6 Warren and Dad drunkenly pulled again (7)
7 Butler with tea seen in service entrance? (7)
8 Bade goodbye; at last, go! (4)
9 Touch antique currency with new moving top (3)
12 Relating to thematic lad spending penny in pig sty (5)
13 Ads disappointing true expert in chemistry (7)
15 Second class mathematician’s method of working with pace (6)
17 Albino affected by divorcing husband (3)
19 Foxy lady, perhaps, booty wrapped in trashy apparel – it’s laced (7)
22 Calm dad becoming tense in key moment at court (6)
25 Tree top destroyed in devastation, too (7)
26 Arab cons radio host - with resistance, without resistance? (7)
28 Charles packing mankini on vacation in cove (5)
29 Negative number, base 14 (3)
31 Those devoted to cub in Thailand provided bone, yes? (6)
32 Showers soak man without hat, in the end (6)
34 Sweet stuff Earl is partial to (5)
36 Chin tax lacking good taste? (5)
37 Restaurateur’s extreme rage about jelly (4)
39 Frau might sell these tiny rats (4)
40 How to behave? (3)

Entries
To enter this competition, input your solution into the website at https://cc.vellender.com before 8th December 2025. The first correct entry drawn from the hat will receive a book from the Chambers range, which has been donated by Chambers.