Related Clues:

• Filler used to close a gap
• Material used for an airtight or watertight join
• It should stop worker going on main line
• Material to stop leaks
• Bond shared between two creatures
• Mammal and insect getting closer?
• Impervious gap filler
• Impervious filler
• Material for plugging leaks
• Filler hardened around aluminium article
• Aquatic insect devouring last of krill, something to fill a gap
• A plug for the trainee - in the main a hard worker
• Gap filler
• Cement-like substance binding insect to mammal
• Main line worker gets protective covering