Very happy or cheerful (6)
I believe the answer is:
blithe
<span class="explanation-format__ClueExplanation">I believe this clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">very happy</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >'<span class="explanation-format__original">cheerful</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(similar in meaning)</span><br/ ><br/ ></span>
(Other definitions for blithe that I've seen before include "Heedless" , "light" , "Light-hearted and good-humoured" , "Innocently happy" , "Merry" .)