smoke-filled room
noun [ C ] uk/ˌsməʊk.fɪld ˈruːm/ /ˌsməʊk.fɪld ˈrʊm/ us/ˌsmoʊk.fɪld ˈruːm/ /ˌsmoʊk.fɪld ˈrʊm/
（政治人物进行密谈决策的）密谈室
a place where powerful people, such as politicians, meet to have discussions and make agreements in secret
The whole business stinks of political corruption and decisions made in smoke-filled rooms. 整个事件充满了政治腐败和密室决策的味道。