Trifle with unpleasant smell and lacking taste (8)
I believe the answer is:
niffnaff
'trifle' is the definition.
(I've seen this before)
'unpleasant smell and lacking taste' is the wordplay.
'unpleasant smell' becomes 'niff' (niff is a kind of smell. I am not sure about the 'unpleasant' bit.**).
'and' says to put letters next to each other.
'lacking taste' becomes 'naff' (I've seen this before).
'niff'+'naff'='NIFFNAFF'
'with' is the link.
(Other definitions for niffnaff that I've seen before include "Trifle" , "Christmas carol" .)