We back a film perhaps (7)
I believe the answer is:
western
'film perhaps' is the definition.
'western' can be an answer for 'film' (I've seen this before). I'm not sure about the 'perhaps' bit.
'we back a' is the wordplay.
I cannot really see how this works, but
'we' is found in the answer.
'back' could be 'stern' (stern is a kind of back) and 'stern' is present in the answer.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for western that I've seen before include "Cowboys and Indians movie" , "Spaghetti film?" , "Type of film or music" , "Old film genre, horse opera" , "direction?" .)