Possible Clues:

• Help to provide a film's sound
• Use or take advantage of assistance
• Advantage of a disguise for the auditor
• Profit made with this, say, in West London?
• Can this help being on the face of it, by the sound of it?
• (To be of) advantage
• Girl given one pound as benefit
• Sounds like the way cover for the face might help
• Advantage that's taken by seven, say
• Use a vocal disguise