Number, a score (6)
I believe the answer is:
twenty
<span class="explanation-format__ClueExplanation">I believe this clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">number</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(twenty is a kind of whole number)</span><br/ ><br/ >'<span class="explanation-format__original">a score</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ ></span>
(Other definitions for twenty that I've seen before include "Figure" , "Number" , "previous clue?" , "made by Q on a light blue square" , "Hundredweights to a ton" .)