Sophisticated town close to Florence (6)
I believe the answer is:
urbane
'sophisticated' is the definition.
(synonyms)
'town close to florence' is the wordplay.
'town' becomes 'urban' (urban means relating to a town or city).
'close to' suggests the final letters (the 'close' to the word).
The final letter of 'florence' is 'e'.
'urban'+'e'='URBANE'
(Other definitions for urbane that I've seen before include "Suave, refined, courteous" , "Cosmopolitan" , "Suavely elegant" , "Polished -- sophisticated" , "Elegant and sophisticated - sounds like city type" .)