Spies found under trains? (8)
I believe the answer is:
sleepers
'spies' is the definition.
(I know this)
'under trains?' is the wordplay.
I cannot really understand how this works, but
'under' could be 'per' (both can mean 'in accordance with') and 'per' is found within the answer.
This may be the basis of the clue (or it may be nonsense).
'found' is the link.
Can you help me to learn more?
(Other definitions for sleepers that I've seen before include "1996 movie" , "Cross-beams on rail tracks" , "Peerless beams for railway tracks" , "Rail track supports" , "Dozers on the train" .)