Old Greek city (6)
I believe the answer is:
sparta
'old greek city' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for sparta that I've seen before include "in ancient Greece" , "Old Greek city state, famous for its citizens' austere lifestyle" , "Ancient Greek city known for warlike spirit" , "Ancient Greek city, capital of Laconia" , "Ancient country" .)