The term FRACTION OF A FRACTION is a mathematical concept that refers to a portion of a fraction. It is a way of expressing a smaller part of a fraction, such as one-fourth of one-half. This concept can be used in many different contexts, such as in dividing a group of people into smaller groups or in measuring the amount of a certain ingredient in a recipe. The crossword solution for this term is SUBPART, which is a synonym for a portion or part of something.