Ruder upsetting article that's disgusting couple, right? (9)
I believe the answer is:
naughtier
'ruder' is the definition.
(rude can mean naughty or disrespectful)
'upsetting article that's disgusting couple right?' is the wordplay.
'upsetting' says the letters should be written in reverse.
'article' becomes 'an' (indefinite article).
'that's disgusting' becomes 'ugh' (I've seen this before).
'couple' becomes 'tie' (I've seen this in another clue).
'right?' becomes 'r' (common abbreviation).
'an' reversed gives 'na'.
'na'+'ugh'+'tie'+'r'='NAUGHTIER'
(Other definitions for naughtier that I've seen before include "More mischievous" , "Less well behaved" , "Worse" , "More badly behaved" , "more unruly" .)