Hit film the kids saw with mum smuggled inside (5)
I believe the answer is:
prang
'hit' is the definition.
'film the kids saw with mum smuggled inside' is the wordplay.
'film the kids saw with mum' becomes 'pg' (abbreviation for Parental Guidance).
'smuggled' becomes 'ran' (I've seen this in other clues).
'inside' is an insertion indicator.
'pg' placed around 'ran' is 'PRANG'.
(Other definitions for prang that I've seen before include "Crash involving a car" , "Possible argument with van" , "Minor shunt" , "Crash (a motor vehicle)" , "Popularly, a motoring contretemps" .)