Film gets a cheer, unexpectedly breaking record (3,5,6)
I believe the answer is:
the great escape
'film' is the definition.
'gets a cheer unexpectedly breaking record' is the wordplay.
'unexpectedly' indicates anagramming the letters.
'breaking' indicates putting letters inside.
'record' becomes 'tape' (taping is a kind of recording).
'gets'+'a'+'cheer'='getsacheer'
'getsacheer' anagrammed gives 'hegreatesc'.
'hegreatesc' placed inside 'tape' is 'THE GREAT ESCAPE'.
(Other definitions for the great escape that I've seen before include "War film" , "picture" .)