vested interest

/ˈves·tɪd ˈɪn·trəst/, /ˈɪn·tər·əst/ n [C]

Definition

› an interest in influencing something so that you can continue to benefit from it: She said the port has a vested interest in protecting the community's environment. › A vested interest is also a person or group who has this type of relationship with something: The British vested interests didn't regulate their own industries, as the Chinese state firms do.

(Definition of vested interest n from the Cambridge Academic Content Dictionary © Cambridge University Press)