One learning about wine region (5)
I believe the answer is:
loire
'wine region' is the definition.
(I've seen this before)
'one learning about' is the wordplay.
'one' becomes 'I' (Roman numeral).
'learning' becomes 'lore' (both can mean tradition or knowledge).
'about' is an insertion indicator.
'i' inserted within 'lore' is 'LOIRE'.
(Other definitions for loire that I've seen before include "department in France" , "French runner" , "Longest French river" , "valley famous for its wines" , "Longest river in France" .)