Greek character has something to bet that needs parking (3)

I believe the answer is:

chi

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'greek character' is the definition.
(letter from the Greek alphabet)

I can't explain the rest of the clue.

(Other definitions for chi that I've seen before include "T'ai -, martial art" , "Twenty-second Greek letter" , "Mental projection" , "Greek letter; Chinese life force" , "character in Thessaloniki" .)

I've seen this clue in The Independent.

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