Smuttier note increasingly snooty beginner dropped (9)
I believe the answer is:
naughtier
'smuttier' is the definition.
(naughty can mean smutty or sexual)
'note increasingly snooty beginner dropped' is the wordplay.
'note' becomes 'n' (abbreviation).
'increasingly snooty' becomes 'haughtier' (haughty means snooty or superior).
'beginner dropped' means to remove the first letter.
'haughtier' with its first letter taken off is 'aughtier'.
'n'+'aughtier'='NAUGHTIER'
(Other definitions for naughtier that I've seen before include "More mischievous" , "Worse" , "Less well behaved" , "more unruly" , "More badly behaved" .)