Vat (4)
'vat' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for tank that I've seen before include "Car fuel container" , "Vat" , "Combat vehicle" , "Armour-plated military vehicle" , "Possible alternative to barrel" .)
(Other definitions for keg that I've seen before include "Sort of beer" , "What's found at King's Head" , "Barrel as for beer" , "Small cask or barrel" , "Small beer cask" .)
'vat' is the definition.
(I know that vat can be written as tub)
This is the entire clue.
(Other definitions for tub that I've seen before include "Maybe it sailed" , "Large plant pot" , "Container, usually for washing" , "Kind of bath" , "Small round container" .)