Very funny appeal by a young girl booked (6)
I believe the answer is:
lolita
'young girl booked' is the definition.
(written about or 'booked' in the novel Lolita)
'very funny appeal by a' is the wordplay.
'very funny' becomes 'lol' (internet acronym for laugh out loud).
'appeal' becomes 'it'.
'by' is a charade indicator (letters next to each other).
'lol'+'it'+'a'='LOLITA'
(Other definitions for lolita that I've seen before include "Nabokov novel about a nymphet" , "novel title" , "1958 novel by Vladimir Nabokov" , "girl described by Nabokov" , "Controversial novel" .)