Tax on goods and service (4)
I believe the answer is:
duty
I believe this clue is a double definition.
'tax on goods' is the first definition.
(I've seen this before)
'service' is the second definition.
(I've seen this before)
'and' acts as a link.
(Other definitions for duty that I've seen before include "Allegiance" , "'Obligation, responsibility (4)'" , "Official obligation" , "Tax on goods" , "Task; military service" .)