Settle account, always after pressure (3)
I believe the answer is:
pay
'settle account' is the definition.
(to settle an account is to pay a bill)
'always after pressure' is the wordplay.
'always' becomes 'ay' (archaic term for 'always').
'after' means one lot of letters go next to another.
'pressure' becomes 'p' (abbreviation).
'ay' put after 'p' is 'PAY'.
(Other definitions for pay that I've seen before include "Remuneration" , "Financial reward" , "Salary, wages" , "stop possible leaks on board" , "Screw" .)