I don’t know: large car missing latest couple of points (6)
I believe the answer is:
umlaut
'couple of points' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
'i don't know large car missing latest' is the wordplay.
I cannot really understand how this works, but
'i' could be 'a' and 'a' is located in the answer.
'large' could be 'l' (eg in clothes sizes) and 'l' is found within the answer.
'car' could be 't' and 't' is found in the answer.
The remaining letters 'umu' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for umlaut that I've seen before include "Germanic accent mark" , "Dots over vowel, as in Koln" , "Mark over vowel in German to indicate change in pronunciation" , "Mark indicating changed vowel value in German" , "German mark over a vowel, consisting of two dots" .)