Prosecuted complicated dues (4)
I believe the answer is:
sued
'prosecuted' is the definition.
(I've seen this before)
'complicated dues' is the wordplay.
'complicated' is an anagram indicator (a complex or confusing ordering of the letters).
'dues' with letters rearranged gives 'SUED'.
(Other definitions for sued that I've seen before include "Started legal proceedings against (someone)" , "Took legal action against" , "taken to court" , "Prosecuted" , "Brought an action against" .)