Dilapidated or ancient vessel (9)
I believe the answer is:
container
'vessel' is the definition.
(I've seen this before)
'dilapidated or ancient' is the wordplay.
'dilapidated' indicates an anagram.
'or'+'ancient'='orancient'
'orancient' with letters rearranged gives 'CONTAINER'.
(Other definitions for container that I've seen before include "Large box for commercial transportation" , "Sort of ship" , "Large shipping box" , "Chest perhaps" , "Vessel" .)