If you describe a group of people as clannish, you mean that they often spend time together and may seem unfriendly to other people who are not in the group.
例句
They were a clannish lot, not given to welcoming strangers.他们那帮人抱成一团，不怎么欢迎生人。
英汉词典释义
adj.
<常贬>(一伙人)自成一帮的;排外的
a clannish family排外的家庭
英英词典释义
Adjective
1. characteristic of a clan especially in being unified;
"clannish loyalty"
2. befitting or characteristic of those who inclined to social exclusiveness and who rebuff the advances of people considered inferior