A quiet new pearl dress (7)
I believe the answer is:
apparel
'dress' is the definition.
(I've seen this before)
'a quiet new pearl' is the wordplay.
'a quiet' becomes 'ap' (I've seen this in other clues).
'new' indicates anagramming the letters.
'pearl' with letters rearranged gives 'parel'.
'ap'+'parel'='APPAREL'
(Other definitions for apparel that I've seen before include "Real pap (anag) - clothing" , "formal dress?" , "what's in the press?" , "Attire" , "Raiment" .)