Smelling no wickedness? Good! (6)
I believe the answer is:
nosing
'smelling' is the definition.
(nosing is a kind of smelling)
'no wickedness? good' is the wordplay.
'wickedness?' becomes 'sin' ('sin' can be a synonym of 'wickedness').
'good' becomes 'g' (abbreviation).
'no'+'sin'+'g'='NOSING'
(Other definitions for nosing that I've seen before include "Moving slowly" , "Sign on (anag)" , "Being inquisitive; advancing slowly" , "like bloodhound on trail" , "going, gradually" .)