Crossword Puzzle Tough-to-hit note

Clue: Tough-to-hit note

Tower of note (e.g. AAA with 3 letters)
Tough test metaphor (ABEAR with 5 letters)
Something very tough (ABEAR with 5 letters)
"What __!": "Tough exam!" (ABEAR with 5 letters)
Tough problem to face? (ACNE with 4 letters)
Tough nut to crack (e.g. ACORN with 5 letters)
Definition of the tonic note word, in a "Sound of Music" song (ADEER with 5 letters)
Tough key for pianists (e.g. AFLAT with 5 letters)
Make a tough choice, with "over" (AGONIZE with 7 letters)
Consider a tough decision, say (AGONIZE with 7 letters)