Whist variant (4)
I believe the answer is:
solo
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">whist variant</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for solo that I've seen before include "Han - (Star Wars); fly unaccompanied" , "Unaccompanied, musically or on adventure" , "Card game; for one" , "By oneself" , "Lone" .)