Halt ice melting - that would be proper (7)
I believe the answer is:
ethical
'proper' is the definition.
(I've seen this before)
'halt ice melting' is the wordplay.
'melting' is an anagram indicator.
'halt'+'ice'='haltice'
'haltice' is an anagram of 'ETHICAL'.
'that would be' acts as a link.
(Other definitions for ethical that I've seen before include "Approved moral behaviour" , "Morally right" , "Morally acceptable" , "Morally proper" , "Morally good or correct" .)