Some superstar vegans have nothing to eat (6)
I believe the answer is:
starve
'have nothing to eat' is the definition.
(I've seen this before)
'some superstar vegans' is the wordplay.
'some' indicates the answer is hidden within the clue (some parts of the word are used).
'STARVE' can be found hidden inside 'superstar vegans'.
(Other definitions for starve that I've seen before include "Without wishing, fast" , "Fail to take in" , "Go hungry" , "Suffer from want of food" , "Averts (anag)" .)