There are soldiers all round one in the carriage (4)
I believe the answer is:
mien
'the carriage' is the definition.
(I've seen this in another clue)
'there are soldiers all round one' is the wordplay.
I cannot really understand how this works, but
'one' could be 'i' (Roman numeral) and 'i' is located in the answer.
'soldiers' could be 'men' (men can mean a group of soldiers) and 'men' is found within the remaining letters.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
'in' is the link.
Can you help me to learn more?
(Other definitions for mien that I've seen before include "Dignified manner" , "Comportment" , "person's look" , "A person's demeanour" , "Appearance is strangely mine" .)