Related Clues:

• 'Move it!'
• ... to the thunder
• Hop to it
• ''Hurry!''
• Order appropriate for 20-, 28- and 44-Across?
• Make a start
• Order to a slacker
• Begin work in earnest
• 'C'mon, chop-chop!'
• Start working
• "Hurry!" (or this puzzle's theme)
• Start something at once
• Begin!
• Act quickly and decisively
• Bestir oneself