Ten dollars for a bird (5)

I believe the answer is:

eagle

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'bird' is the definition.
(eagle is a type of bird)

I don't understand the remainder of the clue.

(Other definitions for eagle that I've seen before include "one's well below par" , "five buck bit, or more" , "Erne, perhaps" , "It may soar" , "Two under in 20 across" .)

I've seen this clue in The Globe and Mail.

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