splinter group       
noun [ C ] uk/ˈsplɪn.tə ˌɡruːp/ us/ˈsplɪn.tɚ ˌɡruːp/
 (政党或其他组织中分裂出的)小派别
a group of people who have left a political party or other organization and formed a new separate organization
  The Socialist Workers' Party seemed to split into several splinter groups. 社会主义工人党似乎分裂成了几个小派别。