Melt, having keys to sort out (7)
I believe the answer is:
defrost
'melt' is the definition.
(I know that defrost is a more specific form of the action melt)
'having keys to sort out' is the wordplay.
'having keys' becomes 'def' (I can't justify this - if you can you should believe this answer much more).
'out' indicates an anagram (out can mean wrong or inaccurate).
'sort' anagrammed gives 'rost'.
'def'+'rost'='DEFROST'
Can you help me to learn more?
(Other definitions for defrost that I've seen before include "Thaw (frozen food)" , "Make free of ice" .)