Crossword Clue:

A beginning an initial part

Answer	Crossword Clue
ACTI	Initial part of a play
ASCENT	Initial part of a roller coaster ride
UPON	Part of a fairy tale beginning.

MATH	Part of an S.A.T.
YOLK	Part of an egg containing vitamin A
SHAREIN	Be a part of, as an experience
GRE	Part of an M.A. program application
BYOB	Part of an invitation to a drinker (abbr.)
MEDIATOR	Part played by an intercessor in a dispute.
BOARD	Part of an American plan, at a hotel
WINDINGTIPS	Part of a manual for an old watch?

REDSEA	Site with an important part in a 1956 film?
BATTENDOWN	Part of an order during a storm at sea.
GIANTSATSIGN	Part of an email address in a California ballpark?
RABBITSFOOT	Part of a furry critter ... and an item suggested by the las
FIFTHWHEEL	Useful type of hitch in a pickup truck, or an undesired part of a social circle