Concerning kidneys (5)
I believe the answer is:
renal
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">concerning kidneys</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for renal that I've seen before include "Pertaining to the kidneys" , "Pertaining to the kidney" , "like kidneys" , "associated with organ" , "Learn (anag) - of organs of the body" .)