The most common and most likely answer to this crossword clue is the 7 letter word GRANGES
I've seen this crossword clue in The Guardian
G
R
A
N
G
E
S
More clues leading to the result GRANGES
Buddy explains!

The straight part
We know that "Country houses" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case country houses = granges.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 GRANGES mean?
GRANGES noun- A granary.
- A farm, with its associated buildings; a farmhouse or manor.
- A lodge of the Patrons of Husbandry, a fraternal organization.