Money going with teachers for sugary snack (8)
I believe the answer is:
'sugary snack' is the definition.
(I know that doughnut is a type of sugary snack)
'money going with teachers' is the wordplay.
'money' becomes 'dough' (dough can informally mean money).
'going with' is a charade indicator (letters next to each other).
'teachers' becomes 'nut' (National Union of Teachers).
'for' acts as a link.
(Other definitions for doughnut that I've seen before include "Jam-filled cake" , "Sweet circular cake" , "Jam-filled bun" , "Small ring-shaped fried cake" , "Fried batter cake" .)