Water in the hose attachment (3)
I believe the answer is:
sea
'water' is the definition.
(sea is a kind of water)
'in the hose attachment' is the wordplay.
'in' indicates a hidden word.
'SEA' is hidden within 'hose attachment'.
(Other definitions for sea that I've seen before include "Eg, Aral, Ross, Irish" , "North, say" , "that's easily reached from Dover?" , "North for one" , "Watery expanse" .)