Related Clues:

• It might be intentional, in baseball
• Street signal directive
• Sign outside a post office
• "Hit the brakes!"
• Exclamation to a pesky sibling
• It may be measured in bushels
• With 28-Across, like some traffic
• "Cut that out!"
• "Go no further!"
• ''Hold it right there!''
• Give in return
• Order on an octagonal sign
• "Hold your horses!"
• "Go no farther!"
• Sign at a RR crossing