其实这并不是省略句，句中的 and Miss Smith he liked the least 属宾语前置，将为强调，将动词 liked 的宾语 Miss Smith 提前至句首了。正常的词序是：

He disliked many of his teachers and he liked Miss Smith the least. 很多老师他都不喜欢, 最不喜欢的是那个女教师史密斯。

又如：

the parts he disliked he would alter and the parts he didn’t dislike he’d leave. 不喜欢的部分他要改变，并非不喜欢的部分他则留下。（句中前面一个 the parts he disliked 其实是动词 alther 的宾语，前面一个 the parts he disliked 其实是动词 leave 的宾语）

当然，如果按你的理解，在 Miss Smith 后面加上 was the one也是一个不错的句子，即说成：He disliked many of his teachers and Miss Smith was the one he liked the least. 这样一来，句中的 the one 是表语，而 he liked the least  就成了修饰 the one的定语从句了。