Rebel among austere activists (5)

I believe the answer is:

react

(Other definitions for react that I've seen before include "What a chemical might do" , "Change chemically" , "Trace (anag)" , "Behave in response" , "provide an answer" .)

I've seen this clue in The Sun.

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.