Buff head (3)
I believe the answer is:
nut
I believe this is a double definition.
'buff' is the first definition.
(both can mean an enthusiast or fan)
'head' is the second definition.
(informal term for somebody's head)
(Other definitions for nut that I've seen before include "Cashew, for example" , "piece of coal" , "Seed with hard shell and firm kernel" , "Hard edible seed" , "keen admirer" .)