Nut — loaf (4)
I believe the answer is:
head
I believe this clue is a double definition.
'nut' is the first definition.
(I've seen this in other clues)
'loaf' is the second definition.
(I've seen this in other clues)
(Other definitions for head that I've seen before include "Froth on beer" , "Edible part of cabbage" , "Leader; water pressure" , "Source of river, leader" , "See 14" .)