Yellow fossil resin (5)
I believe the answer is:
amber
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">yellow fossil resin</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 amber that I've seen before include "Follilised resin" , "Name of female" , "Cautionary colour" , "Cautionary signal" , "Yellow fossil-resin" .)