清君側

Simplified: 清君侧

qīngjūncè ㄑㄧㄥ ㄐㄩㄣ ㄘㄜˋ

    • to remove the treacherous ministers surrounding the monarch (historically used as a pretext for rebellion)

Character by character

Saying俗语俗語

Idiom惯用语 · Rarely used now

Literally
clear out the ruler's flanks
Meaning
Historically, removing treacherous officials around the ruler, often a pretext for rebellion. Now, getting rid of bad people around a leader.

Sources