Reputed to help on starting school (4)
I believe the answer is:
said
'reputed' is the definition.
(said to be, reputed to be)
'help on starting school' is the wordplay.
'help' becomes 'aid' (synonyms).
'on' means one lot of letters go next to another.
'starting' says to take the initial letters.
The initial letter of 'school' is 's'.
'aid' after 's' is 'SAID'.
'to' acts as a link.
(Other definitions for said that I've seen before include "Stated" , "Spoken" , "Port ____, important site in the Suez crisis" , "Mentioned" , "Averred" .)