Former sweetheart (3,5)
I believe the answer is:
old flame
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">former sweetheart</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for old flame that I've seen before include "still 1 across [ALIGHT], it seems" , "Someone once loved" , "Ex-lover - the fire still burns" , "Ex" , "Former partner" .)