餐厅很大很干净的英文表达是 "The restaurant is large and clean."

其中 "large" 是形容词，表示 "大的"；"clean" 是形容词，表示 "干净的"。

这句话的来源是英语语法中的定语从句，用来修饰 "restaurant" 这个名词。

下面是几个带有定语从句的例句，以及它们的中文翻译：

The car that I bought last week is very fast. (我上周买的那辆车很快。)
The book that you recommended to me is very interesting. (你推荐给我的那本书很有趣。)
The house that we pved in before was much smaller. (我们以前住的那幢房子小得多。)