Amateurish player stuffing ex-Wimbledon champion Serena, initially brazen (9)

I haven't cracked this one yet — but the brilliant team at Fifteensquared have:

I think this is: HAM=”Amateurish player (actor)”, inside Monica SELES=”ex-Wimbledon champion”, plus initial of S-erena some research suggests that Monica Seles lost in a Wimbledon final, and did not become champion