Possible Clues:

• Noise from hostile dog
• Grumble increase's ultimately trivial
• Develop primarily loud threatening sound
• Enunciate gruffly
• Low guttural sound
• Expand length and sound menacing
• Odd ones in law court go back to complain
• Sound which threatens to become loud, primarily
• What setter does fifty grand in turnover? Bank intervenes!
• Become large and emit a threatening noise