"The Name of the Rose" author (3)
'the name of the rose author' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for eco that I've seen before include "Green prefix" , "Environmental group" , "Concerned with the environment" , "Umberto -, Italian author (The Name of the Rose)" , "Umberto - - , novelist" .)