Fundamental nature of perfume (7)
I believe the answer is:
essence
I believe this clue is a double definition.
'fundamental nature' is the first definition.
(I've seen this before)
'perfume' is the second definition.
(I know that perfume can be written as essence)
'of' acts as a link.
(Other definitions for essence that I've seen before include "Inner nature of anything" , "Concentrated liquid flavouring" , "Soul" , "Nice fuel" , "Perfume or concentrated extract" .)