African runner's wealthiest, having lost millions (7)

I believe the answer is:

ostrich

'african runner's' is the definition.
(I've seen this in another clue)

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

(Other definitions for ostrich that I've seen before include "Fast winger" , "Runner" , "Someone unprepared to face the facts" , "one tries to hide in the sand" , "One refusing to face facts; flightless African bird" .)

I've seen this clue in The Telegraph.

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