Quick to notice things (9)
I believe the answer is:
observant
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">quick to notice things</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 observant that I've seen before include "aware of surroundings" , "Good at noticing" , "taking things in" , "paying close attention" , "Watchful" .)