"Foucault's Pendulum" author (3)
I believe the answer is:
eco
'foucault's pendulum 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 "Umberto - - , novelist" , "Green prefix" , "Umberto -, Italian author (The Name of the Rose)" , "Umberto --, Italian writer" , "Environmental group" .)