Goat feasibly from Belgium, say (6)
I believe the answer is:
butter
'goat' is the definition.
(something which 'butts')
'belgium say' is the wordplay.
'belgium' becomes 'B' (international vehicle registration code).
'say' becomes 'utter' (to utter something is to speak or say it).
'b'+'utter'='BUTTER'
'feasibly from' acts as a link.
This may not be right. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for butter that I've seen before include "Edible fat" , "& 22 Mincepie accompaniment" , "Milk product" , "goat?" , "(and 4) Kind of toffee" .)