Sweet but crazy, mine has left (6,5)
I believe the answer is:
banana split
'sweet' is the definition.
(banana split is a kind of sweet)
'crazy mine has left' is the wordplay.
'crazy mine has' becomes 'banana' (I can't justify this - if you can you should give a lot more credence to this answer).
'left' becomes 'split' (I've seen this before).
'banana'+'split'='BANANA SPLIT'
'but' is the link.
Can you help me to learn more?
(Other definitions for banana split that I've seen before include "sweet food" , "Ice-cream dish" , "Ice cream dish" , "Fruit and ice cream dessert" .)