Inclination to be crooked (4)
I believe the answer is:
bent
I believe this is a double definition.
'inclination' is the first definition.
(bent is a kind of inclination)
'be crooked' is the second definition.
(similar in meaning)
'to' acts as a link.
(Other definitions for bent that I've seen before include "Crooked - tendency" , "Slang for dishonest or crooked" , "Crooked; disposition" , "Angled; grass" , "Corrupt; grass stalk" .)