The most common and most likely answer to this crossword clue is the 7 letter word UPLANDS
I've seen this crossword clue in The Guardian
U
P
L
A
N
D
S
More clues leading to the result UPLANDS
Buddy explains!

The straight part
We know that "hilly region" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case hilly region = uplands.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.
What does UPLANDS mean?
UPLANDS noun- The area in the interior of a country with a generally higher elevation; often hilly, but not generally mountainous (compare highlands).
- The country, as against the town.