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She's famous as an actress.
Literal
She [topic-は] actress [as-として] famous is.
として marks the capacity or role in which she is famous — specifically as an actress, not in general. This pattern is extremely common for describing someone's identity in a particular domain: 教師として (as a teacher), 日本人として (as a Japanese person), 友人として (as a friend). It often implies the person may have other identities, but this is the one being highlighted.