21a the definition is two words (and pretty poor).
29 - once you have removed the extra you have two words producing the middle three letters then two words producing the three letters that consumes them.
Still don't see 24. & Lit clues are almost always dreadful and should be banned in my view, but as far as I can see that clue makes even less sense than most. It's just a bad straight non cryptic clue as far as I can see. Where are the 2 separate elements?