Reibun
。

My daughter has grown into the dress my wife used to wear.

Literal

Daughter [topic-は] wife [subject-が] was-wearing dress [subject-が] can-wear become.

着られる is the potential form of 着る ('to wear'). The pattern ~ようになる ('come to do') marks the transition into a new capability — 'came to be able to wear.' A sweet observation about a daughter growing into adult size. Embedded relative clause 妻が着ていた modifies ドレス.