Unthinking (8)
I believe the answer is:
mindless
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">unthinking</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for mindless that I've seen before include "Unthinking" , "Silly" , "Stupid" , "Without thought or care" , "Acting with no concern for the consequences" .)