Railway union? (8)
I believe the answer is:
junction
I believe this clue is a double definition.
'railway' is the first definition.
(thesaurus)
'union?' is the second definition.
(junction is a kind of union)
(Other definitions for junction that I've seen before include "Union - joint" , "Motorway exit" , "Point of union" , "Intersection" , "meeting-place" .)