new broom

plural new brooms

1. An employee, especially a manager, that makes great changes to a business.

   In one way, Mr. Brown's position is particularly difficult, because unlike other political leaders he cannot claim to be a new broom. The Economist in article "Labour pains" on Dec 1st 2007

   1 more example

   And soon people noticed that there was a new broom employed at Sweeney’s[.]

   1911, ‘Steel Rudd’, The Book of Dan, Brisbane: University of Queensland Press, published 1970, page 59