Vapours (5)
I believe the answer is:
fumes
'vapours' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for fumes that I've seen before include "Odours" , "Gases ejected as waste products" , "Seethes with anger, smokes (5)" , "Smoulders or smokes" , "Smokes; rages" .)