The term 'PRUNE-to-be' is a crossword solution that consists of two words: 'PRUNE' and 'To-be'. PRUNE is a type of PLUM that has been dried and preserved, while 'To-be' is a verb meaning to exist or to happen in the future. Together, the two words form a phrase that suggests something that is in the process of becoming a PRUNE. This phrase can be used to describe a situation where something is in the process of becoming something else, such as a person who is in the process of becoming successful.