Dark, gloomy (6)
I believe the answer is:
sombre
<span class="explanation-format__ClueExplanation">I believe this is a double definition.<br/ ><br/ >'<span class="explanation-format__original">dark</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >'<span class="explanation-format__original">gloomy</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I've seen this in other clues)</span><br/ ><br/ ></span>
(Other definitions for sombre that I've seen before include "Dark, dull" , "Dull, gloomy" , "Gloomy and dismal" , "Joyless" , "Solemn and grave" .)