A capital ring for a lover (5)
I believe the answer is:
romeo
'for a lover' is the definition.
(I've seen this before)
'a capital ring' is the wordplay.
'a capital' becomes 'rome' (capital of Italy).
'ring' becomes 'o' (letter resembling a ring).
'rome'+'o'='ROMEO'
(Other definitions for romeo that I've seen before include "He's on the lookout for it?" , "He was known for loving" , "Literary lover" , "Tragic lover" , "Casanova" .)