Relative fool (4)
I believe the answer is:
nana
I believe this is a double definition.
'relative' is the first definition.
(I've seen this before)
'fool' is the second definition.
(I've seen this before)
(Other definitions for nana that I've seen before include "Informal grandmother" , "Fool; novel by Zola" , "granny" , "Fool; grandmother" , "Zola tale of a courtesan" .)