Watchful; perceptive (9)
I believe the answer is:
observant
<span class="explanation-format__ClueExplanation">I believe this clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">watchful</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >'<span class="explanation-format__original">perceptive</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(similar in meaning)</span><br/ ><br/ ></span>
(Other definitions for observant that I've seen before include "adhering to religious practices" , "taking things in" , "with a keen eye" , "aware of surroundings" , "(Of music)using conventional keys" .)