stick up for something/someone 
phrasal verb with stick verb uk/stɪk/ us/stɪk/ stuck | stuck
  informal      
C1 支持,捍卫,维护(尤指受到批评的人或物)
to support or defend someone or something, especially when that person or thing is being criticized
  I can stick up for myself. 我能维护我自己。 
 It's sweet the way he sticks up for his little brother. 他维护他小弟弟的样子真讨人喜欢。