Half of a score ... or a perfect score (3)
I believe the answer is:
ten
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">half of a score</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >'<span class="explanation-format__original">a perfect score</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ ></span>
(Other definitions for ten that I've seen before include "X-WORD" , "Roman numeral X" , "time" , "Base of decimal system" , "How many" .)