A French gentleman obtains high-class ointment (7)
I believe the answer is:
unguent
'ointment' is the definition.
(I know that ointment can be written as unguent)
'a french gentleman obtains high-class' is the wordplay.
'a french' becomes 'un' ('a' in French).
'gentleman' becomes 'gent' (gent is a kind of gentleman).
'obtains' means one lot of letters goes inside another.
'high class' becomes 'U' (as in U and non-U speech).
'gent' going around 'u' is 'guent'.
'un'+'guent'='UNGUENT'
(Other definitions for unguent that I've seen before include "Ointment, soothing salve" , "Lotion" , "application" , "Balm, ointment" , "Oily substance" .)