Uncertainty principle physicist (10)
I believe the answer is:
heisenberg
'uncertainty principle physicist' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for heisenberg that I've seen before include "Nobel prize-winner" , "Exact location and speed ever unknown, I suggested" , "'Uncertainty principle' mathematical physicist, d. 1976 -- begins here (anag)" , "Man of principle" , "to give name in uncertainty" .)