Slimy substance (3)
I believe the answer is:
goo
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">slimy substance</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for goo that I've seen before include "Substance that's viscous" , "Viscous matter" , "Sticky or slimy substance" , "Slime" , "Anything sticky" .)