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®

clannishness
     n : tendency to associate with only a select group [syn: {cliquishness},
          {exclusiveness}]