The term 'word before market or circus' can be solved by the four-letter word 'FLEA'. Fleas are small, wingless insects that feed on the blood of mammals and birds. They are known for their ability to jump long distances and are usually found in homes, yards, and other areas where animals live. Fleas are also commonly associated with markets and circuses, as they can often be found in the fur of animals used in these events.