Grandma an idiot? (4)
I believe the answer is:
nana
This clue is a double definition.
'grandma' is the first definition.
(I've seen this before)
'an idiot?' is the second definition.
(I've seen this before)
(Other definitions for nana that I've seen before include "Informal grandmother" , "Grandmother - dog in Peter Pan" , "Fool; novel by Zola" , "Fool; Zola heroine" , "Zola's heroine" .)