An essence (7)
I believe the answer is:
extract
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">an essence</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 extract that I've seen before include "Determine the value of" , "Draw out; excerpt" , "Withdraw - quotation" , "Passage selected from a larger work" , "Extirpate" .)