Related Clues:

• Sing like a bee?
• Utterance at a single unvaried level
• Low sound of bad smell?
• Low continuous sound
• Nasty smell
• Make music through closed lips
• Low, continuous sound
• Make musical sound with closed lips
• Single unvarying note
• If, though sound, it bled, that would have cut it down to size
• This could have bled in a base sort of way
• 'By the sound of it, an addition could make it like us (3)'
• Sound of a fan
• Run nicely
• Second rather than first, lacking variety