One leaves intact vessel in warehouse (8)
I believe the answer is:
entrepot
'warehouse' is the definition.
(type of warehouse or store)
'one leaves intact vessel in' is the wordplay.
'one' becomes 'i' (Roman numeral).
'leaves' indicates named letters should be taken away.
'intact' becomes 'entire' (synonyms).
'vessel in' becomes 'pot' (I can't explain this - if you can you should believe this answer much more).
'entire' with 'i' taken out is 'entre'.
'entre'+'pot'='ENTREPOT'
(Other definitions for entrepot that I've seen before include "Trading port" , "Storehouse" , "Bonded warehouse; port" , "Import/export warehouse, port" .)