Author, good man - still a child (9)
I believe the answer is:
stevenson
'author' is the definition.
(novelist Robert Louis Stevenson)
'good man still a child' is the wordplay.
'good man' becomes 'st' (abbreviation for saint).
'still' becomes 'even' (synonyms).
'a child' becomes 'son' (male child).
'st'+'even'+'son'='STEVENSON'
(Other definitions for stevenson that I've seen before include "Author of 12 2" , "Scottish writer" , "Robert Louis --, Scottish novelist" , "Writer of Treasure Island, d. 1894" , "Robert Louis -, Scots novelist" .)