One female in very influential game of football? (9)

I believe the answer is:

semifinal

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But I can't explain it at all! Could you help me understand?

(Other definitions for semifinal that I've seen before include "Tie" , "big match" , "late stage in contest" , "big game" , "Penultimate round of a competition" .)

I've seen this clue in The Times.

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