Cup tie rearranged: become frosty (3,2)
I believe the answer is:
ice up
'become frosty' is the definition.
(I've seen this in another clue)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for ice up that I've seen before include "Completely freeze" , "become frozen" , "get coat" .)