Poles involved in characteristic movement of goods (7)
I believe the answer is:
Here is my best explanation:
'movement of goods' is the definition.
'poles involved in characteristic' is the subsidiary indication.
'poles' becomes 'ns' (North and South poles).
'involved in' is an insertion indicator.
'characteristic' becomes 'trait' (I've seen this in other clues).
'ns' placed into 'trait' is 'transit'.
(Other definitions for transit that I've seen before include "To pass through/across", "In migration", "A passing across", "Moving", "Passage of planet across the disc of the sun", "Movement (of goods)", "Pass through; van", "Change", "In passing" and "Act of passing across".)