Journalist tried novel: nothing in it (6)
I believe the answer is:
editor
'journalist' is the definition.
(senior journalist)
'tried novel nothing in it' is the wordplay.
'novel' indicates an anagram (letters in a new or novel order).
'nothing' becomes 'O' (O resembles 0).
'in it' is an insertion indicator.
'tried' anagrammed gives 'editr'.
'editr' going around 'o' is 'EDITOR'.
(Other definitions for editor that I've seen before include "Script-preparer" , "Do tire out the newspaper head" , "Chief journalist" , "Redo it and become head of publication" , "cutter?" .)