Go on to become environmental activist (4)
I believe the answer is:
gore
'go on' is the definition.
The answer and definition can be both acts as well as being singular nouns.
Maybe there's an association between them I don't understand?
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for gore that I've seen before include "piece of material" , "Impale" , "stuff from part of Kensington" , "Result of bleeding" , "Pierce with horn - blood" .)