Be loud, perhaps twice as much (6)
I believe the answer is:
double
'twice as much' is the definition.
(I've seen this before)
'be loud perhaps' is the wordplay.
'perhaps' indicates anagramming the letters.
'be'+'loud'='beloud'
'beloud' is an anagram of 'DOUBLE'.
(Other definitions for double that I've seen before include "Second charge for the same offence" , "Dartboard outer score" , "- - -u, (w)" , "Person who says one thing and does another" , "Lookalike; twofold" .)