What does the cryptic crossword clue "Huge region over in USA is Appalachia (4)" mean?

The definition is "Huge". The wordplay uses hidden reversed. Hidden reversed in "huge region over in usA IS Appalachia" The answer is ASIA.

Huge region over in USA is Appalachia (4)

Times Cryptic #26764 | 1 Across | 2017-06-29 flower