Asinine, senseless (5)
I believe the answer is:
inane
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">asinine</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I know that asinine can be written as inane)</span><br/ ><br/ >'<span class="explanation-format__original">senseless</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ ></span>
(Other definitions for inane that I've seen before include "Empty" , "Fatuous, vacuous" , "Mindlessly silly" , "Frivolous" , "Unintelligent" .)