Poles involved in characteristic movement of goods (7)
I believe the answer is:
transit
'movement of goods' is the definition.
'poles involved in characteristic' is the wordplay.
'poles' becomes 'ns' (North and South poles).
'involved in' indicates putting letters inside.
'characteristic' becomes 'trait' (I've seen this before).
'ns' put inside 'trait' is 'TRANSIT'.
(Other definitions for transit that I've seen before include "Act of passing across" , "Passage of a planet across the sun's disc" , "Change" , "The process of going or conveying" , "Start in for the process of being conveyed" .)