Product of infected tissue (3)
I believe the answer is:
pus
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">product of infected tissue</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 pus that I've seen before include "Yellow matter formed in infected wound" , "Product of infected tissue" , "Fluid, a product of inflammation" , "Liquid produced in infected tissue" , "Material in wounds" .)