Engaged coach at terminus of railway (4)

I believe the answer is:

busy

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'engaged' is the definition.
(similar in meaning)

'coach at terminus of railway' is the wordplay.
'coach' becomes 'bus' (synonyms).
'at' says to put letters next to each other.
'terminus of railway' becomes 'y' (I can't explain this - if you can you should give a lot more credence to this answer).
'bus'+'y'='BUSY'

Can you help me to learn more?

(Other definitions for busy that I've seen before include "Fully employed" , "Fully occupied" , "Active, occupied" , "detective" , "With much to do" .)

I've seen this clue in The Guardian.

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