The term 'PART OF A LOCK' can be summarized by two crossword solutions: BOLT (4 letters) and TALON (5 letters). A BOLT is a type of fastener consisting of a threaded shaft and a head, which is used to secure two or more objects together. It is commonly used in locks, where it is inserted into the door frame and the door handle is then attached to the BOLT. A TALON is a curved metal piece that is part of a lock mechanism. It is inserted into the door frame and when the key is turned, the TALON slides into the door handle, preventing it from being opened.