Halt ice melting for good (7)
I believe the answer is:
ethical
'for good' is the definition.
(thesaurus)
'halt ice melting' is the wordplay.
'melting' indicates anagramming the letters.
'halt'+'ice'='haltice'
'haltice' anagrammed gives 'ETHICAL'.
(Other definitions for ethical that I've seen before include "In accordance with approved moral standards" , "Moral, honest" , "lt's available on prescription only" , "Morally good or correct" , "Morally right" .)