Poles appearing in characteristic carriage (7)
I believe the answer is:
transit
'carriage' is the definition.
(thesaurus)
'poles appearing in characteristic' is the wordplay.
'poles' becomes 'ns' (North and South poles).
'appearing in' indicates putting letters inside.
'characteristic' becomes 'trait' (I've seen this before).
'ns' placed into 'trait' is 'TRANSIT'.
(Other definitions for transit that I've seen before include "The process of going or conveying" , "Pass across/through" , "Crossing - passage" , "To pass through/across" , "Pass across" .)