Audibly - audibly permitted (5)
'audibly' is the definition.
(I've seen this before)
'audibly permitted' is the wordplay.
'audibly' shows a homophone (sound like).
'permitted' becomes 'allowed' ('allow' can be a synonym of 'permit').
'allowed' is a homophone of 'ALOUD'.
(Other definitions for aloud that I've seen before include "Not silently or in a whisper", "Not sotto voce", "in a normal voice", "intended for audience", "Not under breath".)