Returning Yankee to preserve notes for all time (8)

I believe the answer is:

eternity

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'all time' is the definition.

I cannot understand how the remainder of the clue works.

(Other definitions for eternity that I've seen before include "Infinite time" , "Time after death" , "life everlasting" , "Endless period" , "Wolfgang Amadeus -" .)

I've seen this clue in The Times.

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