for在这里是连词,意为"因为". , 主语为:their victory , 谓语为:dawns on ,宾语为:the shining new world 。后面的they had dreamed of, cleansed of all human meanness. 是个从句,用于修饰world. 可以变成这样 the shining new world that/which they had dreamed of, cleansed of all human meanness. at best在这里是副词,副词的位置是灵活变动的,你把它暂且移开就比较好理解了。 这个句子用了两个副词,分别为:at best (最多,充其量)和never (从不)结合一起可以翻译为“不管怎样也不”,“无论如何也不”