The lady and the space man who's so intrepid (4)

I believe the answer is:

hero

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

(Other definitions for hero that I've seen before include "Admired champion" , "Chief good guy in a book or film" , "Priestess at Sestos" , "Principal boy" , "Man of valour" .)

I've seen this clue in the Evening Standard.

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