Regular payment of gratuity in dispatch (7)
I believe the answer is:
stipend
'regular payment' is the definition.
(stipend is a kind of regular payment)
'gratuity in dispatch' is the wordplay.
'gratuity' becomes 'tip' (as in a gratuity to a waiter).
'in' indicates putting letters inside.
'dispatch' becomes 'send' (I've seen this in other clues).
'tip' put inside 'send' is 'STIPEND'.
'of' is the link.
(Other definitions for stipend that I've seen before include "Fixed salary" , "Pay (clerical)" , "Soldier's pay" , "Payment for cleric" , "Minister's salary" .)