Regular payment and bonus money put in post (7)
I believe the answer is:
stipend
'regular payment' is the definition.
(stipend is a kind of regular payment)
'money put in post' is the wordplay.
'money' becomes 'tip' (money given for service).
'put in' means one lot of letters goes inside another.
'post' becomes 'send' (synonyms).
'tip' going within 'send' is 'STIPEND'.
'and bonus' is the link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for stipend that I've seen before include "minister's wages" , "Money paid periodically" , "Fixed salary" , "Clergyman's salary" , "Soldier's pay" .)