Coming out of their shells, Brad and Lucy not just loud (7)
I believe the answer is:
raucous
'loud' is the definition.
(thesaurus)
I don't understand the remainder of the clue.
(Other definitions for raucous that I've seen before include "Loud and harsh-sounding" , "harshly loud" , "Shrill - strident" , "Rowdy - strident" , "Unpleasantly loud and harsh" .)