The most common and most likely answer to this crossword clue is the 9 letter word DOOLITTLE
I've seen this crossword clue in Independent
D
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L
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More clues leading to the result DOOLITTLE
- Girl made grand in swindle over small amount
- As reported, mainly idle pupil of professor
- Dustman idle outside Job Centre?
- Eliot told fantastic tale of a friend to animals
- Hugh’s doctor conceals love for fower girl in bet
- Toilet breaks with old Higgins: subject of his bet during play?
- Following party, ring petite Cockney flower girl
- Romeo’s back to idle outside for Eliza
- Old toilet-trained literary parvenu
Buddy explains!

The straight part
We know that "literary parvenu" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case literary parvenu = doolittle.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.