Primatologist's subjects (4)
I believe the answer is:
apes
'primatologist's subjects' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for apes that I've seen before include "Parrots" , "Mimics like primates" , "Large primates" , "Species of primate" , "Peas (anag)" .)