Circuitous route - intend to replace train's first carriage (9)
I believe the answer is:
demeanour
'carriage' is the definition.
The answer and definition can be both human attributes as well as being singular nouns.
Perhaps you can see a link between them that I don't see?
'circuitous route intend to replace train's' is the wordplay.
I cannot quite understand how this works, but
'intend' could be 'mean' (meaning is a kind of intending) and 'mean' is present in the answer.
This explanation may well be incorrect...
'first' acts as a link.
Can you help me to learn more?
(Other definitions for demeanour that I've seen before include "Enamoured of the way a person behaves" , "Behaviour" , "Look" , "Manner of behaving towards others" , "Outward bearing" .)