Complement of socks (4)
I believe the answer is:
pair
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">complement of socks</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 pair that I've seen before include "Duo" , "flight of stairs" , "E.g. two aces; mate" , "Set of two" , "Two ducks in one game of cricket" .)