Dress has a quiet pearl decoration (7)
I believe the answer is:
apparel
'dress' is the definition.
(synonyms)
'a quiet pearl decoration' is the wordplay.
'quiet' becomes 'pp' (music symbol for 'pianissimo').
'pearl decoration' becomes 'arel' (I can't explain this - if you can you should give a lot more credence to this answer).
'a'+'pp'+'arel'='APPAREL'
'has' acts as a link.
Can you help me to learn more?
(Other definitions for apparel that I've seen before include "Fancy gear" , "kit" , "what's in the press?" , "it's generally put on!" , "Clothes - garments" .)