。
She insisted on her innocence.
Literal
She [topic-は] her own blamelessness [object-を] asserted.
潔白 ('blamelessness, purity, innocence in the moral sense') is a more elevated, formal-feeling word for innocence than 無実 or 無罪. Etymologically 'pure-white,' it draws on the long-standing image of moral cleanliness as whiteness. 主張する ('to claim, assert, insist on') is the standard verb for vocally maintaining a position. The pairing belongs to literary or news prose — someone publicly declaring their clean conscience.