A party, meeting or gathering that is exclusively, or with a significant majority of, females.
The female equivalent of a sausage fest
She'd told me there was going to be some hot guys there but it turned out to be a complete clam clan.
Party on girls! Friday night, it's gonna be a Clam Clan so lets go crazy without the partners, k?
A group who has hooked up with the same girl. Especially when a straight guy and a bi-sexual or lesbian chick hook up with the same girl!
Did you hear that Zach and Whitney joined the clam clan, they both hooked up with Rachel this weekend?