I am papa’s naughty child (3)
I believe the answer is:
imp
'naughty child' is the definition.
(informal term for a misbehaving child)
'i am papa's' is the wordplay.
'i am' becomes 'im' ().
'papa' becomes 'P' (phonetic alphabet: alpha, bravo, charlie etc.).
'im'+'p'='IMP'
(Other definitions for imp that I've seen before include "Small devil or sprite" , "Emperor" , "Mischievous child" , "one likely to cause trouble" , "Small demon" .)