Athenians say no good, making smells (5)
I believe the answer is:
reeks
'smells' is the definition.
(reeking is a kind of smelling)
'athenians say no good' is the wordplay.
'athenians say' becomes 'Greeks' (athenian is a kind of Greek).
'no' suggests deleting specific letters.
'good' becomes 'g' (abbreviation).
'greeks' with 'g' taken out is 'REEKS'.
'making' is the link.
(Other definitions for reeks that I've seen before include "Macgillycuddy's - -" , "Stinks to high heaven" , "Smells bad" , "Smells very strongly" , "offensive odours" .)