Hemingway's handle (4)
I believe the answer is:
'hemingway's handle' 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 "one after Oscar" , "Father; P (radio comms.)" , "Mama's other half?" , "Father; letter P" , "Comms code for 'P'" .)