Role in act that is gone (8)
I believe the answer is:
departed
'is gone' is the definition.
(synonyms)
'role in act' is the wordplay.
'role' becomes 'part' (eg a part or role in a film).
'in' is an insertion indicator.
'act' becomes 'deed' (deed is a kind of act).
'part' inserted inside 'deed' is 'DEPARTED'.
'that' acts as a link.
(Other definitions for departed that I've seen before include "Left -- late" , "Dead; set off" , "Went - dead" , "Left, went away" , "Gone, maybe dead" .)