Slate lawyer, bamboo fancier (5)
I believe the answer is:
panda
'bamboo fancier' is the definition.
(pandas eat bamboo)
'slate lawyer' is the wordplay.
'slate' becomes 'pan' (both can mean to criticise strongly).
'lawyer' becomes 'da' (district attorney).
'pan'+'da'='PANDA'
(Other definitions for panda that I've seen before include "Black and white mammal" , "Bamboo-eating animal" , "One eating bamboo" , "Endangered animal" , "Black-and-white bear" .)