Down in the mouth (4)
I believe the answer is:
glum
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">down in the mouth</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for glum that I've seen before include "Miserable" , "Sullen-looking" , "Doleful" , "Dejected, morose" , "Sad and downcast" .)