Nuclear explosive power unit (7)

I believe the answer is:

megaton

(Other definitions for megaton that I've seen before include "Measure of explosive power - montage (anag)" , "Explosive power equivalent to one million tons of TNT" , "it weighs a lot" , "Powerful explosive unit" , "Unit of explosive power" .)

I've seen this clue in The Guardian.

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.