Spooner's badger set forth — became still (9)
I believe the answer is:
stagnated
'became still' is the definition.
The answer and definition can be both to do with fundamental existence as well as being past participle verbs.
Maybe there's an association between them I don't understand?
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for stagnated that I've seen before include "progressed no further" , "Stood still" , "made no progress" , "Vegetated" .)