。
She was kept waiting for over an hour.
Literal
She [topic-は] one-hour-or-more was-made-to-wait.
待たされた is the causative-passive of 待つ — 待つ → 待たせる (causative 'make wait') → 待たされる (causative-passive 'be made to wait'). This double-marked form expresses an unwilling subject forced into the action; in Japanese it almost always carries a negative emotional charge (annoyance, frustration, suffering). The base form for godan verbs contracts: 待たせられる → 待たされる. 一時間以上 ('over an hour') is built with 以上 ('the above-stated quantity and beyond'), a productive suffix for 'X or more.'