Obnoxious class row (4)
I believe the answer is:
rank
I believe this is a triple definition!
'obnoxious' is the first definition.
(thesaurus)
'class' is the second definition.
(I have seen 'Social class ' mean 'rank' so perhaps 'class' could also mean 'rank')
'row' is the third definition.
(I've seen this in other clues)
(Other definitions for rank that I've seen before include "Not qualified to give order" , "Social standing; foul-smelling" , "The military row is coarsely overgrown" , "Stinking" , "Standing; foul smelling" .)