Make watertight (4)
'make watertight' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for caulk that I've seen before include "Make boat waterproof by filling seams" , "Make watertight by sealing joints or seams" .)
'make watertight' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for seal that I've seen before include "Stamp of approval" , "Amphibious sea animal or kind of stamp" , "Sea-dweller can produce a wax impression" , "See 7" , "Fasten with hot wax" .)