That's exactly it Livs - a convoluted 'comp anag'. I'm not sure it works entirely for me since there's no anagram indicator for the last 3 words (or in the definition indicated by the underscoring). But perhaps I'm being too Ximenean.
By the way, 27a - is it 2 indirect anagrams or have I missed the point? I have it as two words meaning 'as a prospect' with a 3 letter word for compete mixed in with a 3 letter word for finish first. (Or as a 3 letter word for compete in 3 letters which when anagrammatised are a word meaning finish first.)