Shipment from A to B (7)
I believe the answer is:
transit
'shipment from a to b' is the definition.
(I've seen this before)
'a to b' is the wordplay.
I cannot really understand how this works, but
'a' could be 'an' and 'an' is located in the answer.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for transit that I've seen before include "Crossing - passage" , "Passage of a planet across the sun's disc" , "Passage of planet across the disc of the sun" , "Pass across" , "Travel" .)