Mail, as a payment (5)
I believe the answer is:
remit
'mail as a payment' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for remit that I've seen before include "Transfer - area of authority" , "The - Papers (M. Amis)" , "committee's brief" , "Defer" , "Scope of reference" .)