Clued up in law arena (5)
I believe the answer is:
aware
'clued up in law arena' is the definition.
The answer and definition are different parts of speech. However, past participle verbs and adjectives can occasionally define each other.
This is all the clue.
Can you help me to learn more?
(Other definitions for aware that I've seen before include "Acquainted with or mindful of" , "Conscious or having knowledge of" , "Bearing in mind" , "Having knowledge of, informed" , "Knowing (of something)" .)