Cologne ingredient (4)
I believe the answer is:
musk
'cologne ingredient' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for musk that I've seen before include "that smells strongly" , "Glandular secretion from a male deer, used in making perfume" , "Scent (for a stag party?)" , "Substance from deer used as basis of perfumes" , "Perfume substance" .)