In the capacity of (3)
I believe the answer is:
qua
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">in the capacity of</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for qua that I've seen before include "In the capacity of (Latin)" , "Sine - non is an indispensable condition" , "Wharf, dock." .)