Coach or supporter (7)
I believe the answer is:
sleeper
This clue could be a double definition.
'coach' is the first definition.
(I know that sleeper is a type of coach)
'supporter' is the second definition.
The answer and definition can be both people as well as being singular nouns.
Maybe you can see a link between them that I can't see?
'or' acts as a link.
Can you help me to learn more?
(Other definitions for sleeper that I've seen before include "Support for railway lines" , "Somnolent person or beam under railway track" , "An overnight train?" , "One who's out" , "Kipper" .)