Exudation from some trees (5)
I believe the answer is:
resin
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">exudation from some trees</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 resin that I've seen before include "varnish, perhaps" , "Very important part of plastics industry" , "Organic polymer used in varnishes, adhesives etc." , "Sap product" , "Contributor to plastics industry" .)