Kitsch outfit dismissed with a sound (5)
I believe the answer is:
schwa
'sound' is the definition.
(I know that schwa is a type of vowel)
'kitsch outfit dismissed with a' is the wordplay.
'outfit' becomes 'kit' (synonyms).
'dismissed' indicates named letters should be taken away.
'with' becomes 'w' (abbreviation).
'kitsch' with 'kit' taken away is 'sch'.
'sch'+'w'+'a'='SCHWA'
(Other definitions for schwa that I've seen before include "Stress-free sound" , "Unstressed vowel (phonetics)" , "Indistinct sound" , "sound unstressed" , "Uh' sound" .)