Half of an umlaut (3)
I believe the answer is:
dot
'half of an umlaut' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for dot that I've seen before include "Shorter of the two signals used in Morse code" , "Morse symbol; spot" , "Internet punctuation mark" , "Point; speck" , "Absolutely punctual, on it" .)