Melt the ice with excellent - no ace - Sunday meal (7)
I believe the answer is:
defrost
'melt the ice' is the definition.
(I've seen this in another clue)
'excellent no ace sunday meal' is the wordplay.
'excellent' becomes 'def' (old-fashioned term for excellent).
'no' indicates named letters should be taken away.
'ace' becomes 'a' (abbreviation).
'sunday meal' becomes 'roast' (I've seen this before).
'roast' with 'a' taken away is 'rost'.
'def'+'rost'='DEFROST'
'with' acts as a link.
(Other definitions for defrost that I've seen before include "Thaw (frozen food)" , "Make free of ice" .)