Related Clues:

• Do some celebrity backing
• Back, as a candidate
• Speak in favor of
• Allay one's fears
• Give support to
• Remove all doubt
• Allay the fears of
• Establish conclusively
• Plug a product, e.g.
• Tell with confidence
• Relieve of anxiety
• Sign the back
• Sign, in a way
• Formally support, as a candidate
• Give approval to