What is the collective noun for clan?

There isn't a specific, widely-accepted collective noun for a clan.

While "clan" itself functions as both singular and plural, you could use more descriptive terms based on the context, such as:

* A gathering of clans

* A confederation of clans

* A brotherhood/sisterhood of clans

* A kinship of clans

Ultimately, the best choice depends on the specific situation and what you're trying to convey.