Heavy role for an actor (4)
I believe the answer is:
lead
I believe this is a triple definition!
'heavy' is the first definition.
(thesaurus)
'role' is the second definition.
(thesaurus)
'for an actor' is the third definition.
(lead is a kind of actor)
(Other definitions for lead that I've seen before include "Take a position in front" , "Metal - van - go ahead" , "pioneer" , "Travel in front of" , "Guide; graphite" .)