Use fine ointment (8)
I believe the answer is:
function
'use' is the definition.
('function' can be a synonym of 'use')
'fine ointment' is the wordplay.
'fine' becomes 'f' (abbreviation).
'ointment' becomes 'unction' (I've seen this before).
'f'+'unction'='FUNCTION'
(Other definitions for function that I've seen before include "What a thing is used for" , "An official ceremony" , "Large formal event" , "Special task - role" , "Work - party" .)