Water conduit (4)
I believe the answer is:
pipe
'water conduit' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for pipe that I've seen before include "Hollow tube or musical instrument" , "Water carrier" , "two hogsheads of wine" , "Wine cask; sing shrilly" , "Means of conveying" .)