Cook's treat (6)
I believe the answer is:
doctor
I believe this is a double definition.
'cook's' is the first definition.
(thesaurus)
'treat' is the second definition.
(doctoring is a kind of treating)
(Other definitions for doctor that I've seen before include "Medical practitioner, for instance" , "Onshore breeze" , "change" , "Medical professional or university don" , "Falsify; quack" .)