Greek philosopher who was tutor to Alexander the Great (9)
I believe the answer is:
aristotle
(Other definitions for aristotle that I've seen before include "Peripatetic teacher" , "Ancient Athenian philosopher, pupil of Plato" , "Great Greek philosopher of 4th century B.C." , "Philosopher - treats oil (anag)" , "Totaliser (anag) - ancient Greek" .)