Possible Clues:

• Words said while shaking hands
• Closing words?
• Done 1 Down? Write that in colour
• "Agreed!" ... and what can be said about the start of the answers to starred clues
• What not to say to the bargain offer
• ''You're on!''
• Statement accompanying a handshake
• ''Let's shake on that''
• 'You've convinced me!'
• Cry while shaking hands