Clothes dismay hosts right before start of event (7)
I believe the answer is:
apparel
'clothes' is the definition.
(synonyms)
'dismay hosts right before start of event' is the wordplay.
'dismay' becomes 'appal' (synonyms).
'hosts' indicates putting letters inside (inserted letters are welcomed or hosted).
'right' becomes 'r' (common abbreviation).
'before' says to put letters next to each other.
'start of' indicates taking the first letters.
The initial letter of 'event' is 'e'.
'r'+'e'='re'
'appal' enclosing 're' is 'APPAREL'.
(Other definitions for apparel that I've seen before include "Clothing, things to wear" , "whatever people have on" , "Attire" , "costume" , "Clothes - garments" .)