Payable now (3)
I believe the answer is:
due
'payable now' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for due that I've seen before include "Payable; deserved" , "Owed, or payable immediately" , "Appropriate - fee - now owing" , "Escort" , "Expected, scheduled" .)