Light-hearted (10)
(Other definitions for insouciant that I've seen before include "Untroubled" , "Light-hearted - in auctions (anag)" , "Not concerned" , "Carefree, heedless" , "Laid-back" .)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">light-hearted</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 playful that I've seen before include "Teasing, unserious" , "In high spirits" , "Frolicsome" , "Fun-loving" , "Frisky" .)
(Other definitions for thaw that I've seen before include "Become friendlier; melt" , "end of the winter?" , "John, once regularly on TV" , "the end of a white Christmas?" , "De-ice" .)