Believes to be guilty but without proof (8)
I believe the answer is:
suspects
'believes to be guilty but without proof' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for suspects that I've seen before include "Is inclined to believe" , "Those under investigation" , "Fears" , "Imagines to be true" , "Believes something might be true" .)