Choose film with shock ending (4)
I believe the answer is:
pick
'choose' is the definition.
(picking is a kind of choosing)
'film with shock ending' is the wordplay.
'film' becomes 'pic' (I've seen this in other clues**).
'with' means one lot of letters go next to another.
'ending' says to take the final letters.
The final letter of 'shock' is 'k'.
'pic'+'k'='PICK'
(Other definitions for pick that I've seen before include "Select - implement" , "Cream" , "Eat very little" , "Choice" , "Pluck" .)