Household hisser (8)
I believe the answer is:
radiator
'household hisser' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for radiator that I've seen before include "House-warmer; engine-cooler" , "It spreads heat around room or cools engine" , "Heater -- or cooler!" , "Its content is wet!" , "Room warmer" .)