A gown-wearing record upset (7)
I believe the answer is:
depress
'upset' is the definition.
(thesaurus)
'a gown-wearing record' is the wordplay.
'a gown' becomes 'dress' (gown is a kind of dress).
'wearing' means one lot of letters goes inside another.
'record' becomes 'EP' (abbreviation for extended play record).
'dress' going around 'ep' is 'DEPRESS'.
(Other definitions for depress that I've seen before include "Make sad or gloomy" , "Sadden" , "Bring down" , "Put dent in or make dismal" , "Push, get, down" .)