The crossword solution for the term 'UNCLE IN A TOP HAT' is SAM. Sam is a common nickname for Samuel, which is a Hebrew name meaning 'God has heard'. Sam is also a popular name in many cultures and is often used as a nickname for people with the name Samuel, Salvatore, Samson, or Salvador. Sam is also a popular character in literature, film, and television, most notably in the Uncle Sam character, who is typically depicted wearing a top hat.