Train bearers (7,5)
I believe the answer is:
railway lines
'bearers' is the definition.
Although both the answer and definition are plural nouns, I can't see how they can define each other.
'train' is the wordplay.
I cannot really see how this works, but
'train' could be 'line' (I've seen this in another clue) and 'line' is found within the answer.
The remaining letters 'railways' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Another definition for railway lines that I've seen is " Groundwork for public transport ...".)