Criticise bill (5)
I believe the answer is:
slate
I believe this clue is a double definition.
'criticise' is the first definition.
(I've seen this before)
'bill' is the second definition.
(thesaurus)
(Other definitions for slate that I've seen before include "Bluish-grey colour" , "Stone used for roofing" , "rock used in building" , "Run down" , "Grey stone; tab" .)