One's occupation may require this regular payment (6)
I believe the answer is:
rental
'payment' is the definition.
(I've seen this before)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for rental that I've seen before include "To do with a letting" , "Cost of hire" , "Amount paid for hire" , "Learnt (anag) -- lease" , "Amount paid for hiring something" .)