A mug to criticise (3)
I believe the answer is:
pan
This clue is a double definition.
'a mug' is the first definition.
(thesaurus)
'criticise' is the second definition.
(informal term meaning to criticise heavily)
'to' acts as a link.
(Other definitions for pan that I've seen before include "Skillet" , "Toilet bowl" , "Wash gravel" , "Try to find gold" , "boil vegetables in this" .)