Unconventional text in sonnet not entirely fanciful (3-8)

'fanciful' is the definition.
(I know that fanciful can be written as non-existent)

'unconventional text in sonnet not entirely' is the wordplay.
'unconventional' indicates an anagram.
'not entirely' means to remove the last letter.
'text'+'in'+'sonnet'='textinsonnet'
'textinsonnet' with its final letter taken away is 'textinsonne'.
'textinsonne' with letters rearranged gives 'NON-EXISTENT'.