Criminal avails discharge (6)
I believe the answer is:
saliva
'discharge' is the definition.
(thesaurus)
'criminal avails' is the wordplay.
'criminal' indicates an anagram.
'avails' is an anagram of 'SALIVA'.
(Other definitions for saliva that I've seen before include "body fluid" , "Clear liquid secreted into the mouth" , "Mouth moisture, spittle" , "Fluid in the mouth" , "Liquid that moistens the mouth" .)