MUDD kicks off the week…
A fun puzzle, with a few pleasing misdirections in the surfaces.
Thanks MUDD!

ACROSS
1. Light-heartedness, that thing constrained by duty (6)
LEVITY
IT (that thing) constrained by LEVY (duty)
4. Watch muscle shown in government (8)
SPECTATE
PEC (muscle) shown in STATE (government)
9. On mother’s ruin, a Latin queen (6)
REGINA
RE (on) + GIN (mother’s ruin) + A
10. Obvious name fits criminal (8)
MANIFEST
12. Blue clothes back in fashion — that’s light beige (4)
SAND
SAD (blue) clothes [fashio]N (back in)
13. Easter animal, cakey? (5)
BUNNY
Double (cryptic) definition
14. I had crusts on large loaf (4)
IDLE
ID (I had) + L[arg]E (crusts on)
17. Surprisingly hot, perhaps — and resistant to pepper, might one say? (12)
UNSEASONABLE
Double (cryptic) definition
20. Pedagogue rude, charmless too (12)
SCHOOLMASTER
23. Clue within these boxes (4)
HINT
24. Female copper? (5)
PENNY
Double (cryptic) definition
25. Join fool in conversation? (4)
KNIT
“nit” = KNIT (fool, “in conversation”)
28. Made public, plant in which meat hidden (8)
REVEALED
REED (plant) in which VEAL (meat) hidden
29. Tacky — and warm, it’s suggested? (6)
UNCOOL
Double (cryptic) definition
30. I go along with gang, thieving (8)
BANDITRY
(I + TRY (go)) along with BAND (gang)
31. Somewhat cunning cutting thickness of rope, say (6)
PARTLY
ART (cunning) cutting PLY (thickness of rope, say)
DOWN
1. Plant bird on egg (8)
LARKSPUR
LARK (bird) on SPUR (egg)
2. Pushing the beastly things aside, Ming vase smashed (8)
VEGANISM
3. Container for fish was whiffy when surface skimmed off (4)
TANK
[s]TANK (was whiffy, when surface skimmed off)
5. Prairie’s struggling, it’s simple (5,7)
PLAIN SAILING
PLAINS (prairie’s) + AILING (struggling)
6. 24 Across, say, one invested in scam (4)
COIN
I (one) invested in CON (scam)
7. Schedule a female, for example, announced? (6)
AGENDA
A + “gender” = GENDA (female, for example, “announced”)
8. Book: there’s novel! (6)
ESTHER
11. Twitching too, as neurone fired (3,2,4,3)
OUT ON ONES EAR
(TOO AS NEURONE)* (*twitching)
15. Fresh — as sriracha? (5)
SAUCY
Double (cryptic) definition
16. Punctured tyre hampers old delivery vehicle (5)
FLOAT
FLAT (punctured tyre) hampers O (old)
18. Be easily visible, also in bold (5,3)
STAND OUT
Double (cryptic) definition
AND (also) in STOUT (bold)
19. Anything but sweet, collaborator with a dose of cruelty (8)
BRUTALLY
BRUT (anything but sweet) + ALLY (collaborator)
21. Angel fish swallowing old sovereign (6)
CHERUB
CHUB (fish) swallowing ER (old sovereign)
22. Full of potholes, perhaps — is that odd? (6)
UNEVEN
Double (cryptic) definition
26. Country music Americans love is always taking the lead (4)
MALI
M[usic] A[mericans] L[ove] I[s] (always taking the lead)
27. South American once in Spain, Catalonia (4)
INCA
[spa]IN CA[atalonia] (once in)
STAND OUT
There seems to be a WP
also=AND
bold=STOUT
AND in STOUT
Thanks KVa@1 I’ve amended
Couldn’t parse REGINA, but since coming here AI has filled me in on the relevant moment in British history.
I learnt a new sauce.
Nothing too taxing, and good fun, as usual for Mudd.
Thanks Mudd for a great set of clues. I found this difficult to start and I finally made headway in the SE corner. After that, the rest gradually fell into place with my top picks being MANIFEST, SAND, PENNY, and BANDITRY. I thought STAND OUT was a weak double definition until I saw the parsing by KVa. Thanks Teacow for the blog.