CLANNISHLY
clannishly, cliquishly
(adverb) in a clannish manner; “these four friends always act clannishly, and don’t let us participate in their activities”
Source: WordNet® 3.1
Etymology
Adverb
clannishly (comparative more clannishly, superlative most clannishly)
In a clannish manner.
Source: Wiktionary
CLANNISH
Clan"nish, a.
Definition: Of or pertaining to a clan; closely united, like a clan;
disposed to associate only with one's clan or clique; actuated by the
traditions, prejudices, habits, etc., of a clan.
– Clan"nish*ly, adv.
– Clan"nish*ness, n.
Source: Webster’s Unabridged Dictionary 1913 Edition