One Greek character or another abandoning university after end of course (7)
I believe the answer is:
epsilon
'one greek character' is the definition.
(letter from the Greek alphabet)
I cannot understand how the remainder of the clue works.
(Other definitions for epsilon that I've seen before include "Foreign character" , "One's lip (anag)" , "Fifth brightest star in a constellation" , "Fifth letter of the Greek alphabet" , "5th letter of the Greek alphabet" .)