Related Clues:

• Buckling down
• Going ___ (fighting)
• Busily working
• Going ___
• Fighting like mad
• Has one's nose to the grindstone
• Going strong
• Causing trouble
• Quarreling
• Busy as a bee
• Get ___ (start work)
• Bickering back and forth
• Busy on a job
• Slaving away
• Squabbling