Take off a piece of underwear concealed by judge (8)
I believe the answer is:
travesty
'take off' is the definition.
(both can mean to imitate or misrepresent)
'a piece of underwear concealed by judge' is the wordplay.
'piece of underwear' becomes 'vest'.
'concealed by' indicates putting letters inside.
'judge' becomes 'try' (as in trialling a defendant).
'a'+'vest'='avest'
'avest' put inside 'try' is 'TRAVESTY'.
(Other definitions for travesty that I've seen before include "Sham" , "Grotesque misrepresentation" , "Grossly unfair representation" , "Grotesque representation" , "Farcical version" .)