Swain, sweetheart (5)
I believe the answer is:
lover
<span class="explanation-format__ClueExplanation">I believe this clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">swain</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(archaic term for a lover)</span><br/ ><br/ >'<span class="explanation-format__original">sweetheart</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(sweetheart can mean a lover)</span><br/ ><br/ ></span>
(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" .)