Even a horrible smell is short-lived (10)
I believe the answer is:
evanescent
'short-lived' is the definition.
(thesaurus)
'even a horrible smell' is the wordplay.
'horrible' indicates an anagram.
'smell' becomes 'scent' (scent is a kind of smell**).
'even'+'a'='evena'
'evena' is an anagram of 'evane'.
'evane'+'scent'='EVANESCENT'
'is' is the link.
(Other definitions for evanescent that I've seen before include "Transient" , "Disappearing" , "slipping away" , "Fleeting" , "Fast-fading" .)