The most common and most likely answer to this crossword clue is the 6 letter word UMLAUT
U
M
L
A
U
T
More clues leading to the result UMLAUT
- Mutual dealt exceptionally in the German mark
- Accent producing mutual confusion
- Mutual exchanges that you reportedly may need in 22 down
- German mark in ultimatum: short period’s left in shake-up
- Top mark in German?
- Decidedly dotty mutual exchange employed by Schrödinger
- Morse I viewed in Düsseldorf, marking a change in pronunciation!
- Hesitation by lout sounding a vowel change
- Key ingredient of Glühwein that’s dotty
- Sign over ä troubled mutual
Buddy explains!

The straight part
We know that "German mark" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case german mark = umlaut.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 UMLAUT mean?
UMLAUT noun- An assimilatory process whereby a vowel is pronounced more like a following vocoid that is separated by one or more consonants.
- The umlaut process (as above) that occurred historically in Germanic languages whereby back vowels became front vowels when followed by syllable containing a front vocoid (e.g. Germanic lūsiz > Old English lȳs(i) > Modern English lice).
- A vowel so assimilated.
- The diacritical mark ( ¨ ) placed over a vowel when it indicates a (rounded) front vowel
- Diaeresis
- To place an umlaut over (a vowel).
- To modify (a word) so that an umlaut is required in it.