Overhead trains (3)
I believe the answer is:
els
'overhead trains' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for els that I've seen before include "Successful owner of several clubs" , "US urban railways" , "Ernie - - (golfer)" , "Golfer; elevated railways" , "Angular distances above the horizon" .)