Casually unconcerned or indifferent (10)
I believe the answer is:
nonchalant
I believe this clue is a double definition.
'casually unconcerned' is the first definition.
(I've seen this before)
'indifferent' is the second definition.
(thesaurus)
(Other definitions for nonchalant that I've seen before include "Uncaring" , "Casual" , "Insouciant" , "Casually calm and relaxed" , "Calmly unconcerned" .)