Sunken ship (5)
I believe the answer is:
wreck
'sunken ship' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for wreck that I've seen before include "Destroy, ruin" , "Demolish; sunken ship" , "Completely spoil" , "Ruin; shatter" , "Destroy; sunken vessel" .)