Inner circle is a term often used for official high-ranking or at least 'influential' groups; it is used whimsically for other close-knit groups. There are other related offerings at http://www.thefreedictionary.com/inner+circle .

Inner circle is a term often used for official high-ranking or at least 'influential' groups; it is used whimsically for other close-knit groups. There are other related offerings at http://www.thefreedictionary.com/inner+circle . Though mafia - 'any tightly knit group of trusted associates' - might be better avoided - and uses 'trusted' in a local sense.