Rank-smelling (5)
I believe the answer is:
fetid
This clue is a double definition.
'rank' is the first definition.
(I've seen this before)
'smelling' is the second definition.
(thesaurus)
(Other definitions for fetid that I've seen before include "Having a stale and unpleasant smell" , "Smelling bad, stinking" , "Stinking, like animal breath" , "Smelly through decay" , "Putrid and stinking" .)