Bounder we arrested pocketing lingerie? (9)
I believe the answer is:
underwear
'lingerie?' is the definition.
(I know that underwear is a type of lingerie)
'bounder we arrested pocketing' is the wordplay.
'pocketing' says the answer is hidden in the clue (I've seen 'pockets' mean this (pocket can mean to contain)).
'UNDERWEAR' is hidden within 'bounder we arrested'.
(Other definitions for underwear that I've seen before include "Garments worn next to the skin" , "Bloomers" , "Lingerie" , "Vests, knickers etc" , "Slip maybe" .)