One of several streets on the London Underground? (4)

I believe the answer is:

bond

(Other definitions for bond that I've seen before include "Fictional agent; link" , "Fastening; secret agent" , "Unite" , "Join; secret agent" , "Valuable asset" .)

I've seen this clue in The Guardian.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.