Cruise ship amenity (3)
I believe the answer is:
spa
'cruise ship amenity' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for spa that I've seen before include "Watering place" , "hydro" , "Health resort at a mineral spring" , "Curative resort" , "A curative mineral spring, or place with one" .)