Person shouting to muffle regularly good singer (8)
I believe the answer is:
yodeller
'singer' is the definition.
(yodeller is a kind of singer)
'person shouting to muffle regularly good' is the wordplay.
'person shouting' becomes 'yeller'.
'to muffle' indicates putting letters inside.
'regularly' means one should take alternating letters (regularly take one letter, leave next etc.).
The alternate letters of 'good' are 'od'.
'yeller' going around 'od' is 'YODELLER'.
(Other definitions for yodeller that I've seen before include "Vocalist" , "Alpine singer" , "Singer using falsetto" , "Mountain air for him" .)