Concerning to listen to emergency service in trains (9)
I believe the answer is:
rehearses
'trains' is the definition.
Although both the answer and definition are verbs in their -s form, I don't understand how they can define each other.
'concerning to listen to emergency service' is the wordplay.
'concerning' becomes 're' (both can mean on a particular topic).
'to listen to' becomes 'hear' (to hear something is to listen to it).
'emergency service' becomes 'ses' (I can't explain this - if you can you should give a lot more credence to this answer).
're'+'hear'+'ses'='REHEARSES'
'in' is the link.
Can you help me to learn more?
(Other definitions for rehearses that I've seen before include "Practises a play" , "not wearing dress till later?" , "Practises as actors do" , "Runs through" .)