Sort of early film (5)
I believe the answer is:
layer
'film' is the definition.
(film can mean a thin layer of something)
'sort of early' is the wordplay.
'sort of' is an anagram indicator.
'early' anagrammed gives 'LAYER'.
(Other definitions for layer that I've seen before include "Source of eggs" , "One of several thicknesses" , "One supplying eggs" , "Blanket - single thickness" , "Film" .)