Two dots over a vowel in German (6)
I believe the answer is:
umlaut
'two dots over a vowel in german' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for umlaut that I've seen before include "Mark over some German letters" , "German mark over a vowel, consisting of two dots" , "Mark indicating changed vowel value in German" , "Germanic accent mark" , "German accent" .)