peg down

knock down a peg

Synonym of take down a notch.

peg the needle

To achieve the maximum level of something, to max out, to pull out all the stops.

square peg in a round hole

Someone or something that does not fit well or at all in a certain setting; a misfit; hence, someone or something that will not succeed in an endeavour, except possibly with much effort and force.

take down a peg

Synonym of take down a notch.