The word or phrase that should be in italics is "Strauss waltz."
The word or phrase that should be in italics in the given sentence is "Strauss waltz." To determine this, we need to identify the specific rule for italicizing titles of musical compositions. According to standard formatting conventions, the titles of longer musical compositions, such as symphonies, operas, and concertos, should be italicized. In this case, "Strauss waltz" refers to a specific musical composition by Strauss, and since it is a longer composition, it should be italicized.
