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[k toonces]

During cluing and editing I somehow double-spaced between clues. Now I can't do anything without "The clue must not contain multiple lines" coming up. How do I remedy this?

[Antony Lewis]

If you can't open Review/Edit Clues (I've never heard this before!), try exporting the file to e.g. Plain text (solution and clues), then editing the file in a text editor to correct any problems, then opening the file.