Homeless wanderer’s saga with new introduction and promise (8)

I believe the answer is:

vagabond

'homeless wanderer's' is the definition.
(I've seen this before)

I can't explain the rest of the clue.

(Other definitions for vagabond that I've seen before include "An idle or dishonest vagrant" , "One having no settled home" , "Roving" , "Traveller of dubious character" , "Down-and-out" .)

I've seen this clue in The Times.

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