Related Clues:

• Having one's nose to the grindstone
• Keep -- (persist)
• Locking horns
• Fighting, often with 'again'
• Up to no good
• Keep ___ (persist)
• Go ___ (tussle)
• In a row
• Keep __ (persist)
• Take a crack __ (try)
• Sparring
• ''Look ___ this way ...''
• Busting one's back
• Having words
• Not procrastinating