Astronomer Newton putting narrative first (5)
I believe the answer is:
sagan
'astronomer' is the definition.
(astronomer and TV presenter Carl Sagan)
'newton putting narrative first' is the wordplay.
'newton putting' becomes 'saga' (I can't justify this - if you can you should believe this answer much more).
'narrative first' becomes 'n' (sst letter of 'narrative').
'saga'+'n'='SAGAN'
(Other definitions for sagan that I've seen before include "US scientist" , "French author" , "Author of Bonjour Tristesse, d. 2004" , "French authoress" , "Astronomer" .)