Nun involved with maniac who comes from northern city? (9)
I believe the answer is:
mancunian
'who comes from northern city?' is the definition.
(someone from Manchester)
'nun involved with maniac' is the wordplay.
'involved with' indicates an anagram (involved can mean confusing or complex).
'nun' anagrammed with 'maniac' can make 'MANCUNIAN'.
(Other definitions for mancunian that I've seen before include "citizen" , "Native of Manchester" .)