Exhausted -- as is American car? (5)

I believe the answer is:

tired

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'exhausted' is the definition.
(I know that exhausted can be written as tired)

I don't understand the rest of the clue.

(Other definitions for tired that I've seen before include "Drowsy" , "Dressed once" , "Worn out" , "Done in" , "ready for bed" .)

I've seen this clue in The Telegraph.

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