Post school result (4)
I believe the answer is:
send
'post' is the definition.
(I know that post can be written as send)
'school result' is the wordplay.
'school' becomes 'S'.
'result' becomes 'end' (I've seen this in another clue).
's'+'end'='SEND'
(Other definitions for send that I've seen before include "Mail" , "Transmit; post" , "Transmit (message)" , "Transport" , "Consign" .)