Railway takes in a light line (3)
I believe the answer is:
ray
'light line' is the definition.
'ray' can be an answer for 'light' (thesaurus). I am unsure of the 'line' bit.
'railway takes in a' is the wordplay.
'railway' becomes 'ry' (abbreviation for railway).
'takes in' means one lot of letters goes inside another.
'ry' placed around 'a' is 'RAY'.
Can you help me to learn more?
(Other definitions for ray that I've seen before include "Man, maybe" , "Beam of light or flat fish" , "Lindwall" , "Gleam" , "Beam; flat-bodied fish" .)