Accent of daughter wearing hat (5)
I believe the answer is:
tilde
'accent' is the definition.
(I've seen this before)
'daughter wearing hat' is the wordplay.
'daughter' becomes 'd'.
'wearing' is an insertion indicator.
'hat' becomes 'tile' (I've seen this before).
'd' going inside 'tile' is 'TILDE'.
'of' acts as a link.
(Other definitions for tilde that I've seen before include "Spanish cedilla" , "Diacritical mark over a letter thus, n" , "Mark, sometimes on keyboards" , "Accent (used over n) in Spanish and Portuguese" , "Wavy line in Spanish" .)