Smell getting round -- grim! (5)
I believe the answer is:
odour
'smell' is the definition.
(synonyms)
'round grim' is the wordplay.
'round' becomes 'o' (round can mean a round object).
'grim' becomes 'dour' (synonyms).
'o'+'dour'='ODOUR'
'getting' is the link.
(Other definitions for odour that I've seen before include "essence" , "Small, aroma" , "Any property detected by the olfactory system" , "pervasive quality" , "Olfactory sensation" .)