"The Simpsons” creator Groening (4)
I believe the answer is:
matt
'the simpsons creator groening' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for matt that I've seen before include "Dull, not shiny" , "(Of surface) dull" , "gospel!" , "book" , "Lacking a shine" .)