Film site chum found so untidy (3,5,2,5)
I believe the answer is:
the sound of music
'film' is the definition.
(I have seen 'feelgood movie' mean 'the sound of music' so perhaps 'movie' could also mean 'the sound of music')
'site chum found so untidy' is the wordplay.
'untidy' indicates anagramming the letters.
'site'+'chum'+'found'+'so'='sitechumfoundso'
'sitechumfoundso' anagrammed gives 'THE SOUND OF MUSIC'.
(Other definitions for the sound of music that I've seen before include "What promgoers like" , "Call of hounds" , "that once enlivened the hills?" , "Film with Julie Andrews" , "feelgood movie" .)