Possible Clues:

• Journalist's style resulting in pedestrian passage?
• Where the road is always up?
• Underground transportation
• Slug oddly born far underground
• The American underground?
• Move around the Tube, essentially underground in America
• Underground in New York, say
• Zigzag by vehicle heading north in US rail system
• Posh bishop and wife in eg New York underground
• US-based franchise, the world’s largest fast food chain