Corpses' nasty smell fades away (6)
I believe the answer is:
bodies
'corpses'' is the definition.
(I've seen this before)
'nasty smell fades away' is the wordplay.
'nasty smell' becomes 'B.O.' (body odour).
'fades away' becomes 'dies' (I've seen this in another clue).
'bo'+'dies'='BODIES'
(Other definitions for bodies that I've seen before include "Corpses or organisations" , "See 12" , "people" .)