Flexed (4)
I believe the answer is:
bent
'flexed' is the definition.
('bend' can be a synonym of 'flex')
This is all the clue.
(Other definitions for bent that I've seen before include "Twisted or crooked" , "Determined - sounds crooked" , "Angled; corrupt" , "Criminal - aptitude" , "Slang for dishonest or crooked" .)