Assist with a B movie? (4)
I believe the answer is:
abet
'assist' is the definition.
(abetting is a kind of assisting)
'with a b movie?' is the wordplay.
'with' means one lot of letters go next to another.
'movie?' becomes 'et'.
'a'+'b' is 'ab'.
'ab'+'et'='ABET'
(Other definitions for abet that I've seen before include "Criminally endorse" , "Make good" , "Assist (a criminal)" , "Aid as in committing crime" , "Give aid to" .)