Lover's capital ring (5)
I believe the answer is:
romeo
'lover's' is the definition.
(I've seen this before)
'capital ring' is the wordplay.
'capital' becomes 'rome' (Rome is an example**).
'ring' becomes 'o'.
'rome'+'o'='ROMEO'
(Other definitions for romeo that I've seen before include "Shakespearean lover" , "''O ..., ..., wherefore are thou ....'' (Shakespeare)" , "A great lover" , "his tragedy one was late?" , "Comms code for R" .)