What's required you must pay finally? (4)
I believe the answer is:
duty
'what's required you must pay finally?' is the definition.
I can't tell whether this definition defines the answer.
'required you must pay finally?' is the wordplay.
'finally?' suggests the final letters (I've seen 'finally' mean this).
The last letters of 'required you must pay' are 'DUTY'.
Can you help me to learn more?
(Other definitions for duty that I've seen before include "Official obligation" , "work you are obliged to do" , "Allegiance" , "Task; military service" , "Financial or work obligation" .)