Silly – light-headed (5)
I believe the answer is:
giddy
<span class="explanation-format__ClueExplanation">I believe this clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">silly</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I know that silly can be written as giddy)</span><br/ ><br/ >'<span class="explanation-format__original">light-headed</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I know that light-headed can be written as giddy)</span><br/ ><br/ ></span>
(Other definitions for giddy that I've seen before include "Dizzy; frivolous" , "Sturdy" , "Frivolous -- liable to fall" , "Frivolous - in a spin?" , "Dizzy - flighty" .)