The Spanish word camarilla means a group of conspirators meeting in secret to manipulate the political leadership. It's been borrowed into English, as well as quite a few other Romance languages, since it's nice to have a word to refer to shadowy backroom dealings.
I imagine the concept would have been familiar to Republican-era Romans, given how much they talk about political corruption and conspiracies. However, the word is most definitely post-Latin.
How would a Roman of Cicero's era refer to such a thing? The obvious cognate is camera plus a diminutive, but I doubt that's attested.