What's gone wrong with lemon, bad fruit (4,5)

'fruit' is the definition.
(I know that Ogen melon is a fruit)

'what's gone wrong with lemon bad' is the wordplay.
I cannot quite understand how this works, but
an anagram of 'gone' is 'ogen' which is present in the answer.
an anagram of 'lemon' is 'melon' which is within the answer.
This accounts for all the letters.
This explanation may well be incorrect...