Tax bar historically — it often sounds the end (4)

I believe the answer is:

toll

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'tax' is the definition.
(I've seen this in other clues)

I don't understand how the rest of the clue works.

(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" .)

I've seen this clue in The Sunday Times and The Times.

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