The most common and most likely answer to this crossword clue is the 5 letter word DUTCH
I've seen this crossword clue in The Times
D
U
T
C
H
More clues leading to the result DUTCH
- National church supporting reduction in tax
- Wife departs with face of tough guy scratched
- East Ender’s wife from the Low Countries?
- Language spoken by a Cockney's wife?
- Wife aggressively masculine, daughter not born
- Cockney wife‘s nationality …
- European partner
- French duke hosts tense husband and wife
- Like house of 24‘s spouse
- Wife has tax cut by Switzerland
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 = dutch.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 DUTCH mean?
DUTCH noun- Wife
- To treat cocoa beans or powder with an alkali solution to darken the color and lessen the bitterness of the flavor.