Fool is one from Italian city (6)
I believe the answer is:
assisi
'italian city' is the definition.
'fool is one' is the wordplay.
'fool' becomes 'ass' (ass is a kind of fool).
'one' becomes 'i' (Roman numeral).
'ass'+'is'+'i'='ASSISI'
'from' is the link.
(Other definitions for assisi that I've seen before include "town, in Italy" , "Home town of St Francis" , "St Francis was born in this Italian town" , "Umbrian town" , "Italian town associated with St Francis" .)