Source : Webster's Revised Unabridged Dictionary (1913)

Clannish \Clan"nish\, a.
   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 : WordNet®

clannishly
     adv : in a clannish manner; "these four friends always act
           clannishly, and don't let us participate in their
           activities" [syn: {cliquishly}]