Old sailing ship (7)
I believe the answer is:
galleon
'old sailing ship' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for galleon that I've seen before include "Trader" , "One might sink" , "Historical warship with three or more masts" , "Large Spanish sailing ship of yore" , "Ship of the line" .)