Possible Clues:

• Sell a bit of a bike on the phone
• Use a bicycle, say? Travelling salesman does!
• Deal in drugs
• Overheard cycle is to sell
• Do one's selling by bike, by the sound of it
• Sell from your bicycle, by the sound of it
• Seel by bike, by the sound of it
• Travel around selling small items
• Dispose of one's wares by bike, perhaps
• Sell one's wares