Record film music first (10)
I believe the answer is:
scoresheet
'record' is the definition.
'film music first' is the wordplay.
'film' becomes 'sheet' (I've seen this before).
'music' becomes 'score' (score is a kind of music**).
'first' is a charade indicator (letters next to each other).
'sheet' put after 'score' is 'SCORESHEET'.
(Other definitions for scoresheet that I've seen before include "Record of players' performances" , "goal to get on this?" .)