Cookie's chocolate morsel (4)
I believe the answer is:
chip
'cookie's chocolate morsel' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for chip that I've seen before include "Gaming counter" , "Gambling counter; golf shot" , "Short lofted golf shot" , "Gambling counter; piece of potato" , "Flaw" .)