reˌvolving ˈdoor noun

1. [countable] a type of door in the entrance of a large building, which goes around and around as people go through it

2. [singular] used to say that the people involved in a situation, organization etc change often:
The park director position has been a revolving door for seven appointees.

3. [singular] used to say that people return to a situation, position etc often, but usually for a different reason:
This could mean that we end up with a revolving door Congress, in which former members return as lobbyists.

[TahlilGaran] Dictionary of Contemporary English ▲

a revolving door
[mainly American]
the movement of people from one organization or activity to another, especially from government jobs to private companies.
Congress has tightened regulations to slow down the revolving door between government and industry.
(often + between)

[TahlilGaran] English Idioms Dictionary ▲