Swain, sweetheart (5)
I believe the answer is:
lover
I believe this clue is a double definition.
'swain' is the first definition.
(archaic term for a lover)
'sweetheart' is the second definition.
(sweetheart can mean a lover)
(Other definitions for lover that I've seen before include "Suitor" , "'Lady Chatterley's - - ' by D H Lawrence" , "Romeo (or Juliet)" , "Boyfriend" , "finished litre first" .)