Take old Christmas film enthusiasts back (7)
I believe the answer is:
snaffle
'take' is the definition.
(I know that snaffle is a more specific form of the action take)
'old christmas film enthusiasts back' is the wordplay.
'old christmas film' becomes 'Elf' (2003 film).
'enthusiasts' becomes 'fans' (fan is a kind of enthusiast).
'back' says the letters should be written in reverse.
'elf'+'fans'='elffans'
'elffans' written backwards gives 'SNAFFLE'.
(Other definitions for snaffle that I've seen before include "Appropriate" , "Kind of bit - take without permission" , "A bit; to grab for oneself" , "A bit; steal (colloq.)" , "Capture" .)