Complex sentence: William the Pious, Duke of Aquitaine formed the first Cluny monastery in 910, with the novel stipulation that the monastery would report directly to the pope rather than to a local lord.
Split into simpler sentences: William the Pious, Duke of Aquitaine formed the first Cluny monastery in 910. He placed with the novel stipulation that the monastery would report directly to the pope rather than to a local lord.