Free traders had leading roles (7)
I believe the answer is:
starred
'had leading roles' is the definition.
'starred' can be an answer for 'had' (starring is a kind of having). I also know that both 'leading' and 'roles' relate to this answer.
'free traders' is the wordplay.
'free' indicates anagramming the letters.
'traders' anagrammed gives 'STARRED'.
(Other definitions for starred that I've seen before include "took the lead part" , "featured prominently" , "Took leading role" , "Took the lead role" .)