The term 'SORT OF CHIMNEY' can be solved by the crossword solution FLUE, which is a four-letter word. A FLUE is a duct or pipe that carries exhaust gases from a fireplace, furnace, water heater, boiler, or other fuel-burning appliance to the outdoors. It is typically made of metal or masonry and is usually lined with clay tile, concrete, or metal. Flues are an important part of a chimney system, as they provide a safe and efficient way to vent hazardous gases away from the home.