Not a Nepali misbehaving — someone else entirely (10)
I believe the answer is:
neapolitan
'someone else entirely' is the definition.
I can't tell whether this defines the answer.
'not a nepali misbehaving' is the wordplay.
'misbehaving' indicates anagramming the letters.
'not'+'a'+'nepali'='notanepali'
'notanepali' anagrammed gives 'NEAPOLITAN'.
(Other definitions for neapolitan that I've seen before include "chocolate" , "Italian citizen" , "From Naples" , "21 [ITALIAN]" , "Italian native" .)