Mama's mama (4)
I believe the answer is:
nana
'mama's mama' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for nana that I've seen before include "Fool; novel by Zola" , "Relative" , "granny" , "Zola's heroine" , "Grandmother - dog in Peter Pan" .)