Movie maker collapsed in one (7)
I believe the answer is:
fellini
'movie maker' is the definition.
(director Federico Fellini)
'collapsed in one' is the wordplay.
'collapsed' becomes 'fell' (I've seen this before).
'one' becomes 'i' (roman numeral).
'fell'+'in'+'i'='FELLINI'
(Other definitions for fellini that I've seen before include "Federico ------- (1920-1993), Italian film director" , "Italian film-maker, d. 1993" , "It. director of Satyricon" , "Federico --, Italian film producer" , "It. film director (La Dolce Vita)" .)