Related Clues:

• Slaved
• Persisted
• Worked like a dog
• Slaved away
• Labored
• Worked
• Hung in there
• Persevered
• Put one's nose to the grindstone
• Worked hard
• Worked a 12-hour shift, e.g.
• Didn't give up
• Slogged away
• Applied elbow grease
• Worked up a sweat