The term 'breaking into a vault' is often used to describe the act of illegally entering a secure area, such as a bank or other financial institution. The crossword solution for this term is 'LEAPING, ' which implies that the person is jumping or otherwise physically entering the vault. This could be done by climbing over a wall or fence, or by using a ladder or other device to gain access. Breaking into a vault is a serious crime and can result in severe legal consequences.