Tidy, without water (4)
I believe the answer is:
neat
This clue is a double definition.
'tidy' is the first definition.
(similar in meaning)
'without water' is the second definition.
(I've seen this before)
(Other definitions for neat that I've seen before include "Straight - cool!" , "Taken without water" , "Very good American" , "Tidy and spruce" , "Trim - tidy - without water" .)