Nobelist Pavlov (4)
I believe the answer is:
ivan
'nobelist pavlov' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for ivan that I've seen before include "Fellow" , "his progress in history was terrible!" , "__ Lendl, Czech-born American tennis star" , "Name of six Russian tzars" , "Vain (anag) - Tsar of Russia" .)