Answer:

thirteen

Answer	Crossword Clue
THIRTEEN	Long dozen, to bakers
THIRTEEN	Coven count
THIRTEEN	Baker's dozen

THIRTEEN	Triskaidekaphobe's fear
THIRTEEN	Missing floor in many hotels.
THIRTEEN	Symbol of an ancient superstition.
THIRTEEN	What a triskaidekaphobe fears.
THIRTEEN	Symbol of bad luck.
THIRTEEN	Important age.
THIRTEEN	Child's milestone age
THIRTEEN	Original number for a nation

THIRTEEN	Thurber's "The ... Clocks"
THIRTEEN	Triskaidekaphobic item
THIRTEEN	Long dozen
THIRTEEN	Baker's dozen quantity
THIRTEEN	Not Lady Luck's number
THIRTEEN	Missing hotel floor?
THIRTEEN	It's not Lady Luck's number
THIRTEEN	Floor number absent in many high-rises

THIRTEEN	Uncommon elevator button
THIRTEEN	Missing button in many an elevator