Humble setters' 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 there's a link between them I don't understand?
'humble setters'' is the wordplay.
'humble' becomes 'demean' (demeaning is a kind of humbling).
'setters'' becomes 'our' (I can't justify this - if you can you should believe this answer much more).
'demean'+'our'='DEMEANOUR'
Can you help me to learn more?
(Other definitions for demeanour that I've seen before include "Behaviour" , "Enamoured of the way a person behaves" , "Manner of behaving towards others" , "Outward bearing" , "Appearance and attitude" .)