Group of students with each admitting a feeling of disgust (6)
I believe the answer is:
nausea
'feeling of disgust' is the definition.
(I've seen this before)
'group of students with each admitting a' is the wordplay.
'group of students' becomes 'nus' (National Union of Students).
'with' is a charade indicator (letters next to each other).
'each' becomes 'ea'.
'admitting' means one lot of letters goes inside another.
'nus'+'ea'='nusea'
'nusea' placed around 'a' is 'NAUSEA'.
(Other definitions for nausea that I've seen before include "Aversion" , "Sensation of queasiness" , "A feeling of disgust or illness" , "Queasy feeling" , "Unpleasant feeling" .)