Frankincense or mastic, for instance (5)
I believe the answer is:
resin
<span class="explanation-format__ClueExplanation">I believe this is a double definition.<br/ ><br/ >'<span class="explanation-format__original">frankincense</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(thesaurus)</span><br/ ><br/ >'<span class="explanation-format__original">mastic for instance</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I know that mastic is a type of natural resin)</span><br/ ><br/ ></span>
(Other definitions for resin that I've seen before include "varnish, perhaps" , "Synthetic compound" , "Rinse out this substance from trees" , "Material exuded from tree" , "frankincense, for instance?" .)