1) Alceste composer 2) Christoph willibald von gluck 3) Composer 4) Impact crater on Mercury 5) La clemenza di Tito composer 6) Pulitzer poet Louise 7) Soprano Alma Found on https://www.crosswordclues.com/clue/gluck
[crater] Gluck is a crater on Mercury. It has a diameter of 105 kilometers. Its name was adopted by the International Astronomical Union in 1979. Gluck is named for the Austrian composer Christoph Willibald Gluck, who lived from 1714 to 1787. ... Found on http://en.wikipedia.org/wiki/Gluck_(crater)
(Reba Fiersohn, Mme. Efrem Zimbalist), 1884–1938, U.S. operatic soprano, born in Rumania. · 1714–87, German operatic composer. · born 1943, U.S. poet. Found on https://www.infoplease.com/dictionary/gluck