Began court proceedings? (6)
I believe the answer is:
served
'began court proceedings?' is the definition.
The answer and definition can be both to do with fundamental existence as well as being past participle verbs.
Perhaps you can see an association between them that I can't see?
This is the entire clue.
Can you help me to learn more?
(Other definitions for served that I've seen before include "Struck opening ball in tennis game" , "In tennis, put the ball in play, or attended to customers" , "Versed (anag)" , "Waited upon" , "Dished up" .)