Wine expert's extremely eccentric business (8)
I believe the answer is:
prosecco
'wine' is the definition.
(I know that Prosecco is a type of Italian wine)
'expert's extremely eccentric business' is the wordplay.
'expert's' becomes 'pro's' (short for professional).
'extremely' suggests removing the centre (only the extremes of the word are used).
'business' becomes 'co' (short for company).
'eccentric' with its middle taken out is 'ec'.
'pros'+'ec'+'co'='PROSECCO'
(Other definitions for prosecco that I've seen before include "Sparkling wine from Italy" , "white wine" , "drink" , "Italian bubbly" .)