Calling to exchange ring for a holiday (8)

I believe the answer is:

vocation

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'calling' is the definition.
(a vocation is a calling)

I cannot understand how the rest of the clue works.

(Other definitions for vocation that I've seen before include "Calling in life" , "A calling as to priesthood (8)" , "Calling, occupation" , "'Career, calling (8)'" , "Occupation, profession" .)

I've seen this clue in The Irish Times.

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