Idiot senior citizen at last turning up the volume (3)
I believe the answer is:
oaf
'idiot' is the definition.
(I've seen this in another clue)
I don't understand the remainder of the clue.
(Other definitions for oaf that I've seen before include "Goon" , "Stupid lout" , "A clumsy boor" , "Lout; dolt" , "Stupid or boorish man" .)