The crossword solution for the term STRIKE UP is INITIATE, which has 8 letters. To INITIATE something means to start or set it in motion. It can be used in a variety of contexts, such as initiating a conversation, initiating a project, or initiating a strike. In this case, the term STRIKE UP is referring to initiating a strike, which is when a group of people stop working in order to protest or demand better working conditions.