Film having problem over copyright (4)
I believe the answer is:
scum
'film' is the definition.
(I know that scum is a type of film)
'problem over copyright' is the wordplay.
'problem' becomes 'sum' (arithmetic problem).
'over' is an insertion indicator.
'copyright' becomes 'C' (as in the copyright symbol, a C in a circle).
'sum' enclosing 'c' is 'SCUM'.
'having' acts as a link.
(Other definitions for scum that I've seen before include "Worthless group of people" , "Dirt on liquid surface" , "Worthless man" , "Dirty froth" , "Film on the surface of a liquid" .)