The crossword solution for the term HOLMES PROP is 'PIPE', which is a four-letter word. A PIPE is a tube or hollow cylinder used to convey fluids, such as water, gas, or steam. It is also used to describe a long, cylindrical tobacco smoking device. The term 'Holmes Prop' is likely a reference to Sherlock Holmes, the fictional detective created by Sir Arthur Conan Doyle. In the stories, Holmes often smoked a PIPE while solving mysteries.