Russian novelist's work diary written up (5)
I believe the answer is:
gogol
'russian novelist's' is the definition.
(author Nikolai Gogol)
'work diary written up' is the wordplay.
'work' becomes 'go' (synonyms).
'diary' becomes 'log' (log can mean a record or diary).
'written up' shows that the letters should be reversed in order (in a down clues, letters go up).
'log' in reverse letter order is 'gol'.
'go'+'gol'='GOGOL'
(Other definitions for gogol that I've seen before include "Nineteenth century Russian author" , "Nikolai ---, Gov't Inspector author" , "The Government Inspector author" , "Dead Souls Russ. author" , "Nikolai -, Russian author (Dead Souls)" .)