Author Umberto (3)
I believe the answer is:
eco
'author umberto' is the definition.
(Umberto Eco, 1932-2016)
This is the entire clue.
(Other definitions for eco that I've seen before include "Concerned with the environment" , "Umberto --, Italian writer" , "Green prefix" , "Environmental group" , "Umberto -, Italian author (The Name of the Rose)" .)