Real Dictionary

shake up
phrasal verb: If someone shakes up something such as an organization, an institution, or a profession, they make major changes to it.

shake-up
the act or an instance of shaking up
to shake in order to mix or loosen
to shake or agitate in order to mix
to shake, esp. so as to mix, blend, or loosen
countable noun: A shake-up is a major set of changes in an organization or a system.
noun: a major set of changes in an organization or a system
noun: a radical or drastic reorganization
noun: a thorough change in a business, department, or the like, as by dismissals, demotions, etc.