Natural disposition to be crooked (4)
I believe the answer is:
bent
This could be a double definition.
'natural disposition' is the first definition.
'bent' can be an answer for 'disposition' (bent is a kind of disposition). I'm not sure about the 'natural' bit.
'be crooked' is the second definition.
(similar in meaning)
'to' is the link.
Can you help me to learn more?
(Other definitions for bent that I've seen before include "Twisted - corrupt" , "Misshapen" , "Morally crooked" , "Sharply curved, grass" , "Crooked - penchant" .)