Painting in spring in old Greek city (6)
I believe the answer is:
sparta
'old greek city' is the definition.
(I've seen this before)
'painting in spring' is the wordplay.
'painting' becomes 'art' (painting is an art).
'in' indicates putting letters inside.
'spring' becomes 'spa' (spa can mean a mineral spring).
'art' going within 'spa' is 'SPARTA'.
'in' is the link.
(Other definitions for sparta that I've seen before include "Formerly "City" , "Ancient Greek city, capital of Laconia" , "found in Ancient Greek location" , "place of austerity" , "in ancient Greece" .)