A northern city in Italy's the state capital (9)
I believe the answer is:
annapolis
'the state capital' is the definition.
(state capital of Maryland)
'a northern city in italy's' is the wordplay.
'northern' becomes 'n' (abbreviation e.g. N. Ireland).
'city in italy's' becomes 'Napoli's' (Italian name for Naples).
'a'+'n'+'napolis'='ANNAPOLIS'
(Other definitions for annapolis that I've seen before include "US state capital" , "Capital of Maryland" , "US city" .)