Improve by studying language in court (6,2)
I believe the answer is:
polish up
'improve' is the definition.
(I've seen this in another clue)
'studying language in court' is the wordplay.
I cannot really understand how this works, but
'language' could be 'polish' (Polish is a language) and 'polish' is present in the answer.
'in court' could be 'up' (up before a judge) and 'up' is located in the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
'by' acts as a link.
Can you help me to learn more?
(Other definitions for polish up that I've seen before include "Work at (something) in order to improve" , "Buff" .)