、。
She grew up to become an outstanding violinist.
Literal
She [topic-は] big became-and, splendid violinist [to-に] became.
Two ~なる ('become') events linked by the te-form: 大きくなって ('grew up') → 立派なバイオリニストになった ('became a splendid violinist'). 立派 is a versatile na-adjective covering 'splendid, fine, admirable, respectable' — applied to people, behavior, or accomplishments. Note the asymmetry: the first becoming uses 大きくなる ('become big' = 'grow up'), the second ~になる ('become a noun'). The two patterns are the two faces of 'becoming X' depending on whether X is an i-adjective or a noun/na-adjective.