noun
clique
KLEEK/kliːk/
A small social group that keeps others out.
The clique at school refuses to let new students join.

Etymology
French clique originally meant a sharp noise and apparently acquired a theatrical group sense through association with claque, a group of hired applauders. This offers a link to the English meaning of an exclusive group.
In context
you had groups of people tightly together and they they ostracized anyone outside the clique
More examples
- An office clique leaves newer employees out of lunch plans.
- The coach discourages cliques and asks everyone to practice together.
- She feels unwelcome around her sister's tight-knit clique.
Forms
clique · cliques
cliquish adjective — Tending to form groups that exclude outsiders.