Case that QC and JP are in, but not barristers (5)
I believe the answer is:
upper
'case' is the definition.
(thesaurus)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for upper that I've seen before include "Nearer the top" , "Part of shoe above sole" , "Higher; more northerly" , "catcher of swans?" , "Higher; part of boot" .)