Old writer in old film (4)
I believe the answer is:
ovid
'old writer' is the definition.
(Roman poet)
'old film' is the wordplay.
'old' becomes 'o' (abbreviation as in OT - Old Testament).
'film' becomes 'vid' (short for video).
'o'+'vid'='OVID'
'in' acts as a link.
(Other definitions for ovid that I've seen before include "Vi, do read the Latin poet" , "Metamorphoses author" , "Writer" , "Old linesman" , "Classical poet" .)