Accents of Dutch wearing dated hats (6)
I believe the answer is:
tildes
'accents' is the definition.
'of dutch wearing dated hats' is the wordplay.
'of dutch' becomes 'tiles' (I can't justify this - if you can you should give a lot more credence to this answer).
'wearing' indicates putting letters inside.
'hats' suggests taking the first letters (in a down clue, the letter at the top of the word).
The first letter of 'dated' is 'd'.
'tiles' placed around 'd' is 'TILDES'.
Can you help me to learn more?
(Other definitions for tildes that I've seen before include "Pronunciation marks over the letter n in Spanish" , "Marks over Ns in Spanish" , "Curly marks" .)