IMPOSSIBLEDREAM

Set to 2 different clues across 2 published puzzles, most often "Man of La Mancha" tune, with "The" — The New York Times, Tuesday, 11 January 2000.

15 letters

Every clue on record, most used first

"Man of La Mancha" tune, with "The"once
The New York Times — Tuesday, 11 January 2000
Song standard from 1966, with "The"once
The New York Times — Friday, 30 August 1996