Vessel on a shark trip (5,3)
I believe the answer is:
noahs ark
'vessel' is the definition.
(I have seen 'Biblical vessel ' mean 'noah's ark' so perhaps 'vessel' could also mean 'noah's ark')
'on a shark trip' is the wordplay.
'trip' indicates an anagram.
'on'+'a'+'shark'='onashark'
'onashark' with letters rearranged gives 'NOAHS ARK'.
(Other definitions for noahs ark that I've seen before include "Biblical ship" , "It landed on Ararat" , "Great biblical boat" , "Huge boat that withstood a great Flood" , "Old Testament water transport" .)