Answer:

key

Answer	Crossword Clue
KEY	Indication
KEY	Lock's partner
KEY	Door opener?

KEY	F or G, but not H
KEY	One of a Florida chain
KEY	One on a ring
KEY	Small island
KEY	It's changed in transposition or modulation
KEY	Locker unlocker
KEY	Vital
KEY	Highly important

KEY	Crucial
KEY	Important
KEY	Indispensable
KEY	What a typist taps
KEY	What to sing in
KEY	F. Scott Fitzgerald's second middle name
KEY	Vitally important
KEY	Test-grading aid

KEY	Lock opener
KEY	A minor, perhaps
KEY	B flat, for one
KEY	Door opener
KEY	Entrance requirement, often
KEY	Solution
KEY	F major or E minor
KEY	Map clarifier

KEY	Opener
KEY	Florida attraction
KEY	Answer book
KEY	C major or D minor
KEY	Critical
KEY	It'll get you in
KEY	Tab, for one
KEY	Computer feature that ends each of the five longest across answers

KEY	A major, e.g.
KEY	Principal tonality, as of a concerto
KEY	Something to play in
KEY	"Defence of Fort McHenry" poet
KEY	Map feature