Source of power (7,6)

I think it could be either:

Which length description are you looking for?:

7,6

steam

'source of power' is the definition.
(I've seen this before)

This is the entire clue.

(Other definitions for steam that I've seen before include "Kettle emission" , "Driving force" , "Vapour from water at boiling point" , "Vaporous exhalation" , "Vapour; energy" .)

I've seen this clue in the Newsday.com, The Times, The Telegraph, The Washington Post, The Guardian, The Mirror and the Wall Street Journal.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.