Inappropriate lack of seriousness (6)
I believe the answer is:
levity
(Other definitions for levity that I've seen before include "Unseriousness" , "Playfulness" , "Frivolousness" , "Lack of seriousness" , "Light-heartedness" .)
I believe the answer is:
levity
(Other definitions for levity that I've seen before include "Unseriousness" , "Playfulness" , "Frivolousness" , "Lack of seriousness" , "Light-heartedness" .)