Relative is a pawnbroker (5)
I believe the answer is:
uncle
I believe this clue is a double definition.
'relative' is the first definition.
(uncle is a kind of relative)
'a pawnbroker' is the second definition.
(old-fashioned term for a pawnbroker)
'is' is the link.
(Other definitions for uncle that I've seen before include "Pawnbroker's nickname" , "older relative" , ". . . . . Sam, the US government" , "Sam, perhaps" , "takes the pledge" .)