Crooked mountain top work shed (4)
I believe the answer is:
bent
'crooked' is the definition.
('bent' can be similar in meaning to 'crooked')
'mountain top work shed' is the wordplay.
'mountain' becomes 'ben' (ben is a kind of mountain**).
'work' becomes 'op' (abbreviation for opus).
'shed' indicates named letters should be taken away ('shed' as in 'cut away').
'top' with 'op' taken out is 't'.
'ben'+'t'='BENT'
(Other definitions for bent that I've seen before include "Slang for dishonest or crooked" , "Crooked; disposition" , "Natural aptitude" , "Dishonest - inclination" , "Crooked; grass" .)