Stupid; senseless (7)
I believe the answer is:
asinine
<span class="explanation-format__ClueExplanation">I believe this is a double definition.<br/ ><br/ >'<span class="explanation-format__original">stupid</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >'<span class="explanation-format__original">senseless</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ ></span>
(Other definitions for asinine that I've seen before include "Stupid (as a donkey?)" , "In the nature of supposedly stupid animal" , "Really silly, ridiculous" , "Extremely stupid or foolish" , "Silly like a donkey" .)