Drowsy; sluggish (9)
I believe the answer is:
lethargic
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">drowsy</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(thesaurus)</span><br/ ><br/ >'<span class="explanation-format__original">sluggish</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(similar in meaning)</span><br/ ><br/ ></span>
(Other definitions for lethargic that I've seen before include "low in vitality" , "Listless" , "Lacking in energy or vitality" , "Unenergetic" , "languid" .)