A score (6)
I believe the answer is:
twenty
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">a score</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for twenty that I've seen before include "Number" , "Score, XX" , "One score" , "with two crosses" , "Figure" .)