The term 'FASTEN A ROPE TO A CLEAT' can be summarized by the word 'BELAY', which is a five-letter word. Belaying is a technique used in rock climbing and mountaineering, where a rope is secured to a cleat or anchor point. This is done to protect the climber from falling and to provide a secure line for the climber to ascend or descend. Belaying is an important safety measure and is essential for any successful climb.