A film about source of sweet or savoury jelly (5)
I believe the answer is:
aspic
'savoury jelly' is the definition.
(I've seen this before)
'a film about source of sweet' is the wordplay.
'film' becomes 'pic' (short for picture).
'about' is a charade indicator (letters next to each other).
'source of' suggests taking the first letters (the start - or source - of the word).
The initial letter of 'sweet' is 's'.
'pic' after 's' is 'spic'.
'a'+'spic'='ASPIC'
'or' acts as a link.
(Other definitions for aspic that I've seen before include "Setter" , "Jelly made with fish or meat stock" , "Preservative jelly" , "Savoury meat or fish jelly" , "Savoury jelly for coating meats and eggs" .)