Forced to regale another personality (5,3)
I believe the answer is:
alter ego
'another personality' is the definition.
'alter ego' can be an answer for 'personality' (I have seen 'Secondary personality ' mean 'alter ego' so perhaps 'personality' could also mean 'alter ego'). I'm unsure of the 'another' bit.
'forced to regale' is the wordplay.
'forced' indicates an anagram.
'to'+'regale'='toregale'
'toregale' is an anagram of 'ALTER EGO'.
Can you help me to learn more?
(Other definitions for alter ego that I've seen before include "Eg, to earl? (Anag)" , "A second personality or intimate friend" , "Similar character" , "To regale other self" , "'One's second self (5,3)'" .)