One Letting Off Steam is a phrase that describes the process of releasing built-up pressure or energy. The crossword solutions for this term are KETTLE (6 letters), IRON (4 letters) and VENTER (6 letters). A KETTLE is a container used for boiling water, usually made of metal or plastic. An IRON is an appliance used to press clothes and remove wrinkles. A VENTER is a device used to release steam or other gases from a system. All three of these items can be used to let off steam in different ways.