Published remarkable children's author (7)
I believe the answer is:
ransome
'children's author' is the definition.
(Swallows and Amazons author Arthur Ransome)
'published remarkable' is the wordplay.
'published' becomes 'ran' (running is a kind of publishing).
'remarkable' becomes 'some' (synonyms).
'ran'+'some'='RANSOME'
(Other definitions for ransome that I've seen before include "Arthur --, English children's author" , "Arthur -, Swallows and Amazons author" , "Author of the Swallows and Amazons books, d. 1967" , "4 ---, children's author" , "He wrote" .)