Having been run over by a train, is unconscious (7)
I believe the answer is:
sleeper
'unconscious' is the definition.
Although both the answer and definition are singular nouns, I don't understand how one could define the other.
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for sleeper that I've seen before include "Dormant potential spy" , "Rail track supporter" , "Earring" , "Spy; part of railway" , "Timber beam" .)