Perfume covering lake, breaking Parisian agreement (9)
I believe the answer is:
patchouli
'perfume' is the definition.
(I know that patchouli is a type of perfume)
'covering lake breaking parisian agreement' is the wordplay.
'covering' becomes 'patch' (patch is a kind of covering).
'lake' becomes 'L' (geographical abbreviation).
'breaking' means one lot of letters goes inside another.
'parisian agreement' becomes 'oui' (I've seen this in another clue).
'l' put inside 'oui' is 'ouli'.
'patch'+'ouli'='PATCHOULI'
(Other definitions for patchouli that I've seen before include "Aromatic oil" , "scented shrub" , "Perfume from the oil of an East Asian shrub - a lit pouch (anag)" , "scented oil" , "essential oil" .)