Good passage in old trading vessel (6)
I believe the answer is:
galley
'trading vessel' is the definition.
(I know that galley is a type of trading vessel)
'good passage' is the wordplay.
'good' becomes 'g' (abbreviation).
'passage' becomes 'alley' (I've seen this before).
'g'+'alley'='GALLEY'
'in old' is the link.
This may not be correct. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for galley that I've seen before include "On-board cooking area" , "Vessel's kitchen" , "Kitchen aboard ship" , "Kitchen on board" , "Cookhouse on board" .)