Dull-colored (4)
I believe the answer is:
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">dull-colored</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 drab that I've seen before include "Drearily dull; slattern" , "Dingy - shabby" , "Cheerless, colourless" , "Colourless like bard" , "Tedious" .)