Northerner's maniac wrestling with nun (9)
I believe the answer is:
mancunian
'northerner's' is the definition.
The answer and definition can be both people as well as being singular nouns.
Maybe there's an association between them I don't understand?
'maniac wrestling with nun' is the wordplay.
'wrestling with' is an anagram indicator.
'maniac' anagrammed with 'nun' gives 'MANCUNIAN'.
Can you help me to learn more?
(Other definitions for mancunian that I've seen before include "Native of Manchester" , "citizen" .)