One unconscious of being run over by a train (7)
I believe the answer is:
sleeper
'train' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'one unconscious of being run over by a' is the wordplay.
'one unconscious of' becomes 'eels' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'being run over' is a reversal indicator (I've seen 'running over' mean this (the letters turn over to the opposite direction)).
'by' is a charade indicator (letters next to each other).
'a' becomes 'per' (eg 'one a day' means 'one per day').
'eels' in reverse letter order is 'slee'.
'slee'+'per'='SLEEPER'
Can you help me to learn more?
(Other definitions for sleeper that I've seen before include "Unactivated spy - railway support" , "provide on-line support?" , "Somnolent person or beam under railway track" , "One who's out" , "Form of transport" .)