a peg on which to hang something

a peg on which to hang something

If you use something as a peg on which to hang your ideas or opinions, you use it to introduce or draw attention to these ideas or opinions. He rarely discusses the book, using it as a peg on which to hang his opinions — and not necessarily those related to the book. These events give opposition spokesmen a peg on which to hang accusations of government mismanagement. Note: This expression can be used to show that the ideas or opinions are not directly relevant to the main subject being discussed.
See also: hang, on, peg, something