Kennedy's Secretary of State (4)
I believe the answer is:
rusk
'kennedy's secretary of state' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for rusk that I've seen before include "Bread baked for babies" , "Baby biscuit" , "Small hard biscuit (for babies)" , "Crisp bread for baby" , "in Bristol Channel" .)