Teakettle output (5)
I believe the answer is:
steam
'teakettle output' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for steam that I've seen before include "Energy (colloq.)" , "Gas formed by vaporizing water at 100?C" , "Kind of power" , "Source of power" , "get very angry" .)