Related Clues:

• Strenuous effort
• Part of the EU said to be after joint effort
• *It may be used with a grunt or two
• All-out effort some might call old
• Dirt on a plumbing fixture?
• Hard work and energy, with erratic bowler's age
• *Vigorous effort
• Effort, metaphorically
• Olive oil for a macaroni salad?