The most common and most likely answer to this crossword clue is the 7 letter word ENTRAIN
E
N
T
R
A
I
N
More clues leading to the result ENTRAIN
- Board in, say, Victoria aren’t randomly elected
- Board mounting paintings in square
- . English currently working to unseat one board
- Board in Victoria sadly aren’t popular
- No inclination to listen to school board
- Card players and coach get on board
- Board of chaps wanting head to leave school
- Board transport in a violent rainstorm
- A number without the ability when rising to get on
- Come down to back section of hospital board
Buddy explains!

The straight part
We know that "to go by rail" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case to go by rail = entrain.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does ENTRAIN mean?
ENTRAIN verb- To draw along as a current does.
- To suspend small particles in the current of a fluid.
- To set up or propagate a signal, such as an oscillation.
- To encarriage, to conjoin, to link; as in a series of entities, elements, objects or processes.
- (neurobiology) To become trained or conditioned in a pattern of brain behavior.
- To get into or board a railway train.
- To put aboard a railway train.