The term 'Ones With Big Shoes To Fill' can be summarized as referring to people who have a difficult task ahead of them, often due to the high expectations of those who came before them. In this case, the crossword solution is 'Clowns', which implies that the person taking on the role of a clown has a lot to live up to in terms of the expectations of the audience. Clowns are often seen as comedic entertainers, so the person taking on the role must be able to provide a level of entertainment that meets or exceeds the expectations of the audience.