Across
Illicit tool criminal concealed in sponge (7)
I haven't cracked this one yet — but Fifteensquared have:
anagram/"criminal" of (tool)*, in BEG="sponge" as a verb
Stomach-churning musical great (7)
I haven't cracked this one yet — but Fifteensquared have:
definition: a nickname for jazz musician Louis Armstrong anagram/"churning" of (Stomach)*
Keen to restrict Neddy’s revelry (7)
Court can, if reconstituted in the capital (7)
I haven't cracked this one yet — but Fifteensquared have:
definition: "Court" as a verb anagram/"if reconstituted" of (can)*; in ROME="the capital" of Italy
12a
Working with board that supports constitutional procedures (9,5)
See 11
Material leak covered up by discontented tabloid (5)
I haven't cracked this one yet — but Fifteensquared have:
WEE="leak" (as in 'take a leak'); inside T-[abloi]-D "discontented" i.e. with its contents / inner letters removed
Ill, Mark’s failing to meet objective (3,6)
Outline something commonly associated with moon (new) (9)
Barge below rocks (5)
I haven't cracked this one yet — but Fifteensquared have:
anagram/"rocks" of (below)*
23a
Not wanting to incriminate myself I take it? (5,9)
See 22
Staggeringly rich? (7)
Taxes on the vacated port (7)
Marine creature managed to turn over by itself almost (7)
Screen made of reeds or bananas (7)
Down
Solemn type enters competition to claim a wicket (4,3)
Indecent old book site (7)
Tarzan’s means of getting around a pin-up? (5)
I haven't cracked this one yet — but Fifteensquared have:
definition: a LIANA is a vine – definition refers to the fictional character Tarzan [wiki] moving between trees swinging on vines A (from surface) + NAIL="pin"; all reversed "up"
Western female at border with oil rich peninsula (9)
I haven't cracked this one yet — but Fifteensquared have:
GAL="Western female" + LIP="border" + anagram/"rich" of oil for GAL, "Western" as in the genre of film for the anagram indicator, "rich" can mean 'ridiculous', 'absurd' e.g. ('that's rich coming from you!')
Brat presenting second short broadcast (5)
Casual and tense, by chance? That’s to invite bad luck (5,4)
Accessory of workman getting the sack (7)
Public welcomes each cut? Get stuffed! (7)
Inclination to pass on ground wheat dish (5,4)
I haven't cracked this one yet — but Fifteensquared have:
anagram/"ground" of (wheat dish)*
Hot air from this nut with an old gun (3,6)
Orange-yellow shifts for fans (7)
Gag writer’s ultimate neckwear (7)
I haven't cracked this one yet — but Fifteensquared have:
MUFFLE="Gag" as a verb + ultimate/last letter of [write]-R
Maybe Brian’s not so great in the sack (7)
Evidence of liquid nitrogen in contaminated sweets (7)
I haven't cracked this one yet — but Fifteensquared have:
N (nitrogen) in anagram/"contaminated" of (sweets)*
One needs to blend honey (5)
Comparatively boring towel? (5)
Type letters or click words in the clue