Part of the railroad I'd sing about (6)
I believe the answer is:
siding
'part of the railroad' is the definition.
'siding' can be an answer for 'railroad' (thesaurus). I am not sure about the 'part of the' bit.
'i'd sing about' is the wordplay.
'about' indicates putting letters inside.
'id' going within 'sing' is 'SIDING'.
Can you help me to learn more?
(Other definitions for siding that I've seen before include "Railway spur" , "Stretch of railway used to store trains" , "passing track" , "Railway marshalling area" , "Where coaches may be" .)