Exhaust what's needed for spare change in Vegas? (4)

I believe the answer is:

tire

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'exhaust' is the definition.
(I know that exhaust can be written as tire)

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

(Other definitions for tire that I've seen before include "Get weary" , "Grow weary of rite" , "Wear out" , "Exhaust" , "Become weary" .)

I've seen this clue in The Telegraph.

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