The Collaborative International Dictionary of English v.0.48:

cliquish \cli"quish\ (kl[=e]"k[i^]sh), a.
   Of or pertaining to a clique; disposed to from cliques;
   exclusive in spirit. -- Cli"*quish*ness, n.
   [1913 Webster]

WordNet (r) 3.0 (2006):

cliquish
    adj 1: befitting or characteristic of those who incline to
           social exclusiveness and who rebuff the advances of
           people considered inferior [syn: clannish, cliquish,
           clubby, snobbish, snobby]

Moby Thesaurus II by Grady Ward, 1.0:

23 Moby Thesaurus words for "cliquish":
   arrogant, clannish, cliquey, contemptuous, contumelious,
   disdainful, elect, ethnocentric, exclusive, haughty, scornful,
   select, selective, sneering, sniffy, snobbish, snobby, snooty,
   snotty, supercilious, toploftical, toplofty, withering