Crossword Clue:

to write in a secret code

Answer	Crossword Clue
CIPHER	Message written in a secret code
IGPAYATINLAY	Secret code, in the secret code
ELO	Band name heard in Morse code on its single "Secret Messages"

ANTIMASONIC	Political party formed in 1828 to oppose the power of a secret society
ENCODE	Write, as a secret message
AREA	Code that's not a secret
HOBO	Bygone traveler with a secret code