Answer:

yabba

Answer	Crossword Clue
YABBA	Flintstone yell starter
YABBA	Start of Fred's yell
YABBA	..... dabba do

YABBA	Start of a Stone Age yell
YABBA	Stone Age toon word
YABBA	Word in a Flintstone yell
YABBA	Start of a Flintstone cry
YABBA	Start of Fred Flintstone's cry
YABBA	Start of a '60s TV toon yell
YABBA	Start of a Flintstone cheer
YABBA	Start of Fred Flintstone's shout

YABBA	"... dabba doo!"
YABBA	Start of a Fred Flintstone cry
YABBA	Beginning of a Flintstones cry
YABBA	Start of a cartoon cry
YABBA	Start of a prehistoric yell?
YABBA	'-- dabba doo!'