Factory tub (3)
I believe the answer is:
vat
'factory tub' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for vat that I've seen before include "Large container for liquid" , "Liquid storage receptacle" , "Large vessel for storing liquids and a large tax" , "Large tank; purchase tax" , "Large barrel" .)