Without costume, cross water (8)
I believe the answer is:
irrigate
'water' is the definition.
(I know that water can be written as irrigate)
'without costume cross' is the wordplay.
'without' indicates putting letters inside.
'costume' becomes 'rig' (I've seen this in other clues).
'cross' becomes 'irate' (both can mean angry).
'rig' going into 'irate' is 'IRRIGATE'.
(Other definitions for irrigate that I've seen before include "wet regularly" , "Supply water (to crops) in channels" , "Bring water to (crops)" , "Artificially supply land with water" , "Water land to stimulate growth" .)