Writer of a hot novel about upper-class Romeo (6)
I believe the answer is:
'writer' is the definition.
'a hot novel about upper-class romeo' is the wordplay.
'novel' indicates anagramming the letters.
'about' means one lot of letters goes inside another.
'upper-class' becomes 'u' (similar in meaning).
'romeo' becomes 'R' (phonetic alphabet: alpha, bravo, charlie etc.).
'hot' with letters rearranged gives 'tho'.
'tho' put inside 'ur' is 'uthor'.
'of' is the link.
(Other definitions for author that I've seen before include "Writer of a book or play", "Originator", "Dramatist", "Someone who originates, causes or initiates something", "Write".)