The most common and most likely answer to this crossword clue is the 4 plus 6 letter word EAST ANGLIA
I've seen this crossword clue in Financial Times
E
A
S
T
A
N
G
L
I
A
More clues leading to the result EAST ANGLIA
- Region where Lamb's full of a singular flavour
- Alias agent used in part of this country
- Algae isn’t a disaster in fenland region
- Region in which eating alas is terrible
- Tales again are going round UK region
- Choppy sea more confused, we hear, in part of England
- Large part of England turning against ale
- Part of the country is against ale brewing
- Endless confusion in European part of the world, here in the UK?
- Lamb infused with a singular flavour in British region
Buddy explains!

The straight part
We know that "Region" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case region = east anglia.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.