most of the +n.使唔使複數?

most of the 後的名詞是要複數的，但視乎該名詞是否可數和有沒有複數式。

most of the children (child 的複數)
most of the fish (fish 是複數)
most of the food (不可數)

clientele 屬 collective noun，本身已是 all the customers 的意思，是不用加 s 的。

most of the clientele 岩。

建議你用
the majority of the clientele
而不用
most of the clientele

may be most of the clientele

hope i can help you