Hit hosted by school, a musical (3)
I believe the answer is:
lam
'hit' is the definition.
(to 'lam' means to hit hard)
'hosted by school a musical' is the wordplay.
'hosted by' says the answer is hidden in the clue (the answer is hosted or welcomed by the clue).
'LAM' is hidden within 'school a musical'.
(Other definitions for lam that I've seen before include "pelt" , "Thump; leg it" , "Go on the - - , (US sl.)" , "hurried flight" , "Escape, get away" .)