Stole hat to hide wig (9)
I believe the answer is:
liberated
'stole' is the definition.
Although both the answer and definition are past participle verbs, I can't see how one could define the other.
'hat to hide wig' is the wordplay.
'hat' becomes 'lid' (lid can informally mean a hat).
'to hide' indicates putting letters inside.
'wig' becomes 'berate' (I can't justify this - if you can you should give a lot more credence to this answer).
'lid' enclosing 'berate' is 'LIBERATED'.
Can you help me to learn more?
(Other definitions for liberated that I've seen before include "Released" , "Emancipated" , "let loose" , "Having stolen" , "Freed from social conventions" .)