Leaving a student some food (5)
I believe the answer is:
offal
'some food' is the definition.
(offal is a kind of food)
'leaving a student' is the wordplay.
'leaving' becomes 'off' (as in 'I'm off').
'student' becomes 'L' (as in L-plates for learner drivers).
'off'+'a'+'l'='OFFAL'
(Other definitions for offal that I've seen before include "Edible liver or heart of animal" , "cheap meat" , "Liver, kidney, etc, as food" , "Waste parts of a carcass" , "Internal organs of an animal used as food" .)