Dastardly (6)
I believe the answer is:
craven
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">dastardly</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for craven that I've seen before include "Contemptibly cowardly" , "Cowardly, abjectly afraid" , "Mean-spirited" , "Chicken-hearted" , "Without backbone" .)