Possible Clues:

• Service person putting iodine in join
• Person in a company
• Serviceman finds one in metal alloy
• Regular breakfast time dipper?
• Engaged by a major employer in private
• One going inside to join private, perhaps
• Regular join should include one?
• Serviceman flogged, one hears, on a regular basis
• Tommy or GI Joe?
• Join admitting one's mercenary?