Tube for transferring liquid from one container to another (6)
I believe the answer is:
siphon
(Other definitions for siphon that I've seen before include "A bottle that squirts, say soda water" , "Tube taking fluid from higher to lower point" , "Tube used to remove liquid from a higher to a lower level" , "Bottle from which a liquid is forced by pressure of gas" , "On ship (anag)" .)