Party that's horrible with teachers' group providing something to eat (8)
I believe the answer is:
doughnut
'something to eat' is the definition.
(doughnut is a kind of food)
'party that's horrible with teachers' group' is the wordplay.
'party' becomes 'do' (do is a kind of party).
'that's horrible' becomes 'ugh' (expression of disgust).
'with' is a charade indicator (letters next to each other).
'teachers' group' becomes 'nut' (National Union of Teachers).
'do'+'ugh'+'nut'='DOUGHNUT'
'providing' acts as a link.
(Other definitions for doughnut that I've seen before include "Small tasty cake with hole in middle" , "Jam-filled bun" , "Sweet fried cake" , "Small ring-shaped fried cake" , "Small circular cake" .)