Ear piece used by Anglo-Belgian (4)
I believe the answer is:
lobe
'ear piece' is the definition.
(I've seen this in another clue)
'used by anglo-belgian' is the wordplay.
'used by' indicates a hidden word.
'LOBE' can be found hidden inside 'anglo belgian'.
(Other definitions for lobe that I've seen before include "Division of the lungs or brain" , "Part of ear or leaf" , "Piece of ear" , "Rounded projection of a larger structure" , "Leaf division" .)