Casually unconcerned or indifferent (10)
I believe the answer is:
nonchalant
<span class="explanation-format__ClueExplanation">I believe this clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">casually unconcerned</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >'<span class="explanation-format__original">indifferent</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(thesaurus)</span><br/ ><br/ ></span>
(Other definitions for nonchalant that I've seen before include "Uncaring" , "Casual" , "Insouciant" , "Casually calm and relaxed" , "Calmly unconcerned" .)