Hidden again in court (6)
I believe the answer is:
covert
'hidden' is the definition.
('covert' can be similar in meaning to 'hidden')
'again in court' is the wordplay.
'again' becomes 'over' (as in the phrases 'start over' and 'start again').
'in' means one lot of letters goes inside another.
'court' becomes 'ct'.
'over' going into 'ct' is 'COVERT'.
(Other definitions for covert that I've seen before include "Undercover, secret" , "Secret - thicket" , "Hidden - thicket" , "Not acknowledged" , "Thicket; not displayed" .)