Crazy attempt on prize (8)
I believe the answer is:
crackpot
'crazy' is the definition.
(I've seen this before)
'attempt on prize' is the wordplay.
'attempt' becomes 'crack' (crack is a kind of attempt).
'on' is a charade indicator (letters next to each other).
'prize' becomes 'pot' (I've seen this in other clues).
'crack'+'pot'='CRACKPOT'
(Other definitions for crackpot that I've seen before include "Eccentric (colloq.)" , "Informal eccentric like damaged utensil" , "Eccentric; impractical" , "Crank" , "Crazy or impractical person" .)