Yin counterpart (4)
I believe the answer is:
yang
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">yin counterpart</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 yang that I've seen before include "Yin's counterpart" , "Complement of yin" , "positive force" , "Yin counterpart" , "Positive element in traditional Chinese philosophy" .)