Lack of proper seriousness (6)
I believe the answer is:
levity
(Other definitions for levity that I've seen before include "Silliness" , "Lack of seriousness" , "Disrespectful humour" , "thoughtlessness" , "Light quality" .)
I believe the answer is:
levity
(Other definitions for levity that I've seen before include "Silliness" , "Lack of seriousness" , "Disrespectful humour" , "thoughtlessness" , "Light quality" .)