Stupid and silly (7)
I believe the answer is:
fatuous
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">stupid and silly</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 fatuous that I've seen before include "Stupid and silly" , "Foolish, inane" , "Silly and pointless" , "Witless" , "Foolish or silly" .)