Crossword Puzzle Alto opening

Clue: Alto opening

Workplaces where there are some openings: Abbr. (ORS with 3 letters)
Opening up completely (BARINGONESSOUL with 14 letters)
Descartes opening (COGITO with 6 letters)
Opening track of "The Beatles' Second Album" (ROLLOVERBEETHOVEN with 17 letters)
Giant opening? (e.g. FEE with 3 letters)
Eye-opening problem? (STYE with 4 letters)
Mural opening? (INTRA with 5 letters)
Music for it is written largely in alto clef (VIOLA with 5 letters)
Big opening? (MEGA with 4 letters)
Lord's Prayer opening (OUR with 3 letters)