Organ that secretes (5)
I believe the answer is:
gland
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">organ that secretes</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 gland that I've seen before include "Organ that separates substances from blood" , "liver, for example" , "Organ that releases essential substances into the bloodstream" , "vital structure" , "Organ that secretes" .)