put a lid on (something)
To keep the level of something from increasing drastically or beyond what is undesirable or dangerous. They were one of the few countries in the EU able to put a lid on unemployment during the recession. The dictator has put a tight lid on protests and public criticism of the government.
keep/put a/the ˈlid on something
try to make sure that people do not do something or find out about something: The government wants to keep the lid on discussion of tax reforms at the moment.