If you describe a group of people as ~, you mean that they often spend time together and may seem unfriendly to other people who are not in the group. (INFORMAL)
They were a ~ lot, not given to welcoming strangers.
= cliquey
ADJ
CLANNISH
Meaning of CLANNISH in English
Collins COBUILD. Толковый словарь английского языка для изучающих язык Коллинз COBUILD (международная база данных языков Бирмингемского университета) . 2012