Assist in Beatles movie (4)
I believe the answer is:
help
This clue is a double definition.
'assist' is the first definition.
(I know that assist can be written as help)
'beatles movie' is the second definition.
(I've seen this in another clue)
'in' is the link.
(Other definitions for help that I've seen before include "Contribute to the success of" , "Assistance" , "Beatles single" , "Beatles' album; assist" , "Be of benefit to" .)