Relating to fusion or fission (7)

I believe the answer is:

nuclear

(Other definitions for nuclear that I've seen before include "small family?" , "With dangerous weapons" , "Relating to atomic structure" , "one's immediate family?" , "Type of reaction" .)

I've seen this clue in The Times.

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.