Wicked cracking safe in court interior (9)
I believe the answer is:
nefarious
'wicked' is the definition.
(similar in meaning)
'cracking safe in court interior' is the wordplay.
'cracking' indicates an anagram.
'interior' means to look at the middle letters.
The centre of 'court' is 'our'.
'safe'+'in'+'our'='safeinour'
'safeinour' is an anagram of 'NEFARIOUS'.
(Other definitions for nefarious that I've seen before include "Extremely wicked" , "immoral?" , "Villainous" , "Very bad" , "Wicked, criminal" .)