Film in shadow (5)
I believe the answer is:
ghost
I believe this clue is a double definition.
'film' is the first definition.
(Ghost is a 1990 film)
'shadow' is the second definition.
(I know that ghost is a type of shadow)
'in' is the link.
(Other definitions for ghost that I've seen before include "Write for another" , "someone without much presence" , "Writer who gives the credit of authorship to someone else" , "author for someone" , "Author, secretly" .)