Tea is such an important part of British culture that we have an entire meal ______ (create) that we have entirely dedicated to our afternoon tea.

第一个 that 是用于构成  such...that...句式。

第二个 that 是关系代词（先行词是 meal），用作 dedicated 的宾语（注意搭配dedicate sth to sth）。

请注意网友句子中的 dedicated 后没有宾语，很显然，这个宾语就是关系代词 that。另外注意have an entire meal created，它的基本结构属于 have sth done。

Tea is such an important part of British culture that we have an entire meal created that we have entirely dedicated to our afternoon tea.

茶是英国文化中很重要的组成部分，以至于我们专门弄出了完整的一餐饭，这就是我们的下午茶。

Tea is such an important part of British culture that we have an entire meal creation that we have entirely dedicated to our afternoon tea.

主句:Tea is such an important part of British culture

从句:that we have an entire meal creation that we have entirely dedicated to our afternoon tea.

备注(1):从句修饰主句作结果状语，such为前位限定词，that为连词引导结果状语从句,第1个that引导结果状语从句，第2个that引导定语从句。

We have an entire meal creation that we have entirely dedicated to our afternoon tea.【that引导定语从句】

备注(2):关系代词that引导限制性定语从句，关系代词that指代an entire meal creation,并在定语从句作谓语动词have dedicated的宾语

【1】We have an entire meal creation【主句】

【2】We have entirely dedicated an entire meal creation to our afternoon tea.【定语从句】

备注(3):把定语从句宾语an entire meal creation用that替代，并放到定语从句句首，然后在放到主句后面获得以下句子。【dedicate A to B 结构】

We have an entire meal creation that we have entirely dedicated to our afternoon tea.