The most common and most likely answer to this crossword clue is the 6 letter word AFGHAN
I've seen this crossword clue in The Guardian
A
F
G
H
A
N
More clues leading to the result AFGHAN
- Type of hound a devotee keeps in Grand Hotel
- Dog blanket
- Dog’s coat
- Hang out under crafts’ centre making woollen blanket
- Two articles about three consecutive letters for Asian citizen
- Good and hot, wrapped in a warmer blanket
- Hang out with a fellow Asian
- National articles
- Dog given a name after a series of letters
- Hound’s two articles
Buddy explains!

The straight part
We know that "National" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case national = afghan.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 AFGHAN mean?
AFGHAN noun- A blanket or throw, usually crocheted or knitted.
- A type of iced chocolate biscuit, sometimes containing cornflakes and topped with a walnut.