Tax bar historically — it often sounds the end (4)
I believe the answer is:
toll
'tax' is the definition.
(I've seen this in other clues)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for toll that I've seen before include "Peal, chime" , "Ring - duty" , "Tax paid for use of some roads" , "Fee for the use of a road or bridge" , "Bridge or road charge" .)