A locked passage is a type of waterway that is closed off from the rest of a body of water, usually by a gate or lock. The term can also refer to a passage that is blocked off by a physical barrier, such as a door or wall. In this case, the crossword solution for the term 'Locked Passage' is 'CANAL, ' which is a man-made waterway used for transportation, irrigation, and other purposes. Canals are often lined with locks, which are used to control the flow of water and allow boats to pass through.