Possible Clues:

• Partner and antagonist with back-to-back theatre jobs
• Mate
• Mate getting into top position
• Workmate's potty, bouncing up and down
• Counterpart gets work one way and another
• 'Pees ’n ’ose', said mate
• Pawnshop 'pottery pieces' are china
• Surgery, evidently reversible, seen in China
• Colleague has a lot of cannabis after work
• Pilot goes hither and thither to find China