Sparta rival (6)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
athens
'sparta rival' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for athens that I've seen before include "foreign city" , "EU capital" , "Site of the Parthenon" , "European capital city" , "Tan she got in Greece" .)