Sentient (5)
I believe the answer is:
aware
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">sentient</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 aware that I've seen before include "Alert, conscious of" , "Knowing (of something)" , "Conscious, sentient" , "Cognizant" , "Apprised or informed" .)