Coach line supporter (7)
I believe the answer is:
sleeper
I believe this clue is a double definition.
'coach' is the first definition.
(sleeper is a kind of coach)
'line supporter' is the second definition.
(a railway line is supported by sleepers)
(Other definitions for sleeper that I've seen before include "film not successful at first" , "Form of transport" , "Possibly ring" , "Supporting block on railway track" , "Express tears over one" .)