Unfroze or melted (6)
I believe the answer is:
thawed
I believe this clue is a double definition.
'unfroze' is the first definition.
('thaw' can be a synonym of 'unfreeze')
'melted' is the second definition.
('thaw' can be a synonym of 'melt')
(Other definitions for thawed that I've seen before include "Unfroze, melted" , "Melted like spring snow" , "Melted like snow or ice" .)