The term 'Stage of a Plan' can be summarized as a PHASE in the process of achieving a goal. It is a step that must be taken in order to move forward and progress towards the desired outcome. The crossword solution for this term is 'PHASE', which is defined as a period or stage in a process of change or development. This term is often used in project management, where each PHASE of a plan is broken down into smaller tasks that must be completed in order to reach the end goal.