Rebellion at university over climbing (8)
I believe the answer is:
uprising
'rebellion' is the definition.
(I know that rebellion can be written as uprising)
'at university over climbing' is the wordplay.
'at university' becomes 'up' ('up' can mean studying at university).
'over' is a charade indicator (letters next to each other) (in a down clue, some letters go over others).
'climbing' becomes 'rising' ('rise' can be a synonym of 'climb').
'up'+'rising'='UPRISING'
(Other definitions for uprising that I've seen before include "Insurrection, rebellion" , "Insurrection or revolt" , "Rebellion, revolt" , "A revolting action?" , "revolution" .)