Proposal one before court entered in flawless film (6,7)
I believe the answer is:
motion picture
'film' is the definition.
(I know that film can be written as motion picture)
'proposal one before court entered in flawless' is the wordplay.
'proposal' becomes 'motion' (proposal at a meeting).
'one before' is a charade indicator (letters next to each other).
'court' becomes 'ct' (abbreviation used in road names).
'entered' is an insertion indicator.
'in flawless' becomes 'piure' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'ct' put into 'piure' is 'picture'.
'motion'+'picture'='MOTION PICTURE'
(Other definitions for motion picture that I've seen before include "Cinema film" , "Movie" , "entertainment" , "Double Indemnity, say" , "Film (US)" .)