"hit song writing business," 1908, from tin pan, slang for "a decrepit piano" (1882). The original one was 28th Street in New York City, home to many music publishing houses.
A reference to the popular music industry in the United States; the term is not used as much today as it was a generation or two ago.
Note: Tin Pan Alley is often associated with songwriters who are more interested in making money off their songs than in producing high-quality music.
A telephone call •Chiefly in the expression give someone a tinkle (1938+)
To urinate; pee •A nursery use (1950+)