Number in a quartet (4)
I believe the answer is:
four
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">number in a quartet</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 four that I've seen before include "Set of bridge players?" , "Perfect square" , "Number of Eliot Quartets" , "teatime?" , "Cube root of 64" .)