Pupil of Plato (9)
I believe the answer is:
aristotle
'pupil of plato' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for aristotle that I've seen before include "Philosopher - treats oil (anag)" , "polymath" , "Old Greek teacher" , "Peripatetic teacher" , "Totaliser for the great Greek philosopher of old" .)