Dish - nuts left in mine (6,5)
I believe the answer is:
banana split
'dish' is the definition.
'nuts left in mine' is the wordplay.
'nuts' becomes 'bananas' (as in crazy).
'left' becomes 'l' (common abbreviation).
'in' indicates putting letters inside.
'mine' becomes 'pit' (down the pit).
'l' going inside 'pit' is 'plit'.
'bananas'+'plit'='BANANA SPLIT'
(Other definitions for banana split that I've seen before include "Ice cream dish" , "sweet food" , "Fruit and ice cream dessert" , "Ice-cream dish" .)