an exclusive group
clique - group
The word ‘clique’ refers to a small circle of people who spend a lot of time together and are typically openly unfriendly and even hostile to those not within their group. They also tend to look out for those in their set exclusively and think little of the needs or feelings of others. For that reason, this term is used to express disapproval.
I’ve found it hard to settle in my new job because there is a clique in the office who simply refuse to engage with me.
There is a clique at the top of the organization and the only way to advance your career is to win their favour.
The students in the class do not mix with each other as a group. At lunchtime, you can see them divided into a lot of different cliques who sit separately from each other.