Great film about a criminal (8)
I believe the answer is:
bigamist
'criminal' is the definition.
(someone married to more than one person)
'great film about a' is the wordplay.
I cannot quite understand how this works, but
'great' could be 'big' (similar in meaning) and 'big' is located in the answer.
'film' could be 'mist' (to film over is to mist or fog over) and 'mist' is located in the answer.
'about' could be 'a' (abbreviation in Chambers) and 'a' is located in the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for bigamist that I've seen before include "member of two unions" , "Person who marries while still married to another" , "One who marries more than once illegally" , "One with a partner too many" , "One with two other halves?" .)