Hi.
Is there a word that is commonly used before "customer" like "crowd" in "a crowd of people"?
We can say "a crowd of people" but that doesn't mean that "crowd" is the collective term for "people". There are other words we could use there, such as "throng", "group", "gaggle" and, no doubt, several more.
I can't think of a natural term that would be used with customers, except maybe a "queue" if you're talking about people waiting to be served in a supermarket.
Some nouns have collective terms but they're normally animals:
- a gaggle of geese (when on the ground)
- a skein of geese (when flying)
- a parliament of owls
- a prickle of porcupines
- a flock of sheep
- a herd of cows
There are some amusing fake ones - an indecision of politicians, for example.