Project a very loud voice (6)
I believe the answer is:
affair
'project' is the definition.
(thesaurus)
'a very loud voice' is the wordplay.
'very loud' becomes 'ff' (musical abbreviation).
'voice' becomes 'air' (I've seen this before).
'a'+'ff'+'air'='AFFAIR'
(Other definitions for affair that I've seen before include "connected with love" , "A romantic intrigue" , "Concern -- extramarital relationship" , "Event; fling" , "Clandestine romance" .)