Reveal school method (4)
I believe the answer is:
show
'reveal' is the definition.
('show' can be a synonym of 'reveal')
'school method' is the wordplay.
'school' becomes 's'.
'method' becomes 'how' (**).
's'+'how'='SHOW'
(Other definitions for show that I've seen before include "Demonstrate; spectacle" , "Demonstrate - parade" , "Display; prove" , "The world of entertainment" , "Expose" .)