Joined by railway (3)
I believe the answer is:
met
'joined' is the definition.
(meeting is a kind of joining)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for met that I've seen before include "gathered together" , "Encountered, came into contact" , "Came together, encountered" , "London police (abbr) - New York Museum of Art (abbr)" , "Encountered or touched" .)