The office of the waiter on the vessel (11)
I believe the answer is:
stewardship
'the office' is the definition.
(stewardship is a kind of office)
'waiter on the vessel' is the wordplay.
'waiter' becomes 'steward' (I've seen this before).
'on' is a charade indicator (letters next to each other).
'the vessel' becomes 'ship' (ship is a kind of vessel).
'steward'+'ship'='STEWARDSHIP'
'of the' acts as a link.
(Other definitions for stewardship that I've seen before include "Management or care (of something)" , "Management of somebody else's property" , "Administration of property, finance etc" , "Job for resigned MP" .)