Singing couples
I believe the answer is:
duos
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">singing couples</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 duos that I've seen before include "Pairs" , "people like Simon and Garfunkel" , "braces" .)