Secret surplus revealed in court (6)
I believe the answer is:
covert
'secret' is the definition.
(similar in meaning)
'surplus revealed in court' is the wordplay.
I cannot really see how this works, but
'surplus' could be 'over' (I've seen this before) and 'over' is located in the answer.
'court' could be 'ct' (abbreviation used in road names) and 'ct' is present in the leftover letters.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for covert that I've seen before include "Hidden - thicket" , "Concealed - flock of coots" , "Secret - thicket" , "18 [HIDDEN]" , "Concealed like fox's liar" .)