Answer: sournote

AnswerCrossword Clue
SOURNOTE

It's not well-pitched

SOURNOTE

Off-pitch tone

SOURNOTE

Flautist's fluff

SOURNOTE
Bad thing to strike
SOURNOTE
It's unpleasant to end on one
SOURNOTEDiscordant tone
SOURNOTEThis is anathema to the maestro: 2 wds.
SOURNOTESinger's lapse
SOURNOTETrumpeter's blooper
SOURNOTEUnpleasant thing to hit
SOURNOTEPianist's "clinker"
SOURNOTEBit of unpleasantness
SOURNOTEUnpleasant ending