Student, once being briefly with nothing to eat, being forgotten (8)
I believe the answer is:
oblivion
'being forgotten' is the definition.
(I've seen this before)
I don't understand how the rest of the clue works.
(Other definitions for oblivion that I've seen before include "The state of being unconscious of what is happening" , "State of being totally unconscious" , "State of being totally forgotten" , "State of being altogether forgotten" , "Obscurity" .)