Ban this crook liquor (7)
I believe the answer is:
absinth
'liquor' is the definition.
(absinth is a kind of liquor)
'ban this crook' is the wordplay.
'crook' is an anagram indicator (a crooked or broken form of the letters).
'ban'+'this'='banthis'
'banthis' is an anagram of 'ABSINTH'.
(Other definitions for absinth that I've seen before include "Potent liqueur, originally made with wormwood" , "Strong liqueur with wormwood and anise" , "(Originally) a wormwood-based liqueur" , "Shrubby plant" , "Potent green aniseed-flavoured spirit" .)