Famous physicist (8)
I believe the answer is:
einstein
'famous physicist' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for einstein that I've seen before include "Albert, who founded the theory of relativity" , "Scientific genius" , "Famous scientist of the nineties" , "Great scientist, founded theory of relativity" , "Nineties (anag.)" .)