Account subtraction (5)
I believe the answer is:
debit
'account subtraction' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for debit that I've seen before include "Sum removed from a bank account" , "left-side entry" , "Accounting entry showing amount spent" , "Enter in accounts as sum owed" , "Accounting entry recording sums that are 5" .)