Mama's mate (4)
I believe the answer is:
papa
'mama's mate' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for papa that I've seen before include "Comms code for 'P'" , "Father; P (radio comms.)" , "Mama's other half?" , "Dad" , "Father; letter P" .)