Crossword Genius

Cease-fire. No UFOs but a very bad crime (1,7,7)

Ross

I believe the answer is:

a serious offence

I'm a little stuck... Click here to teach me more about this clue!

'cease-fire no ufos but a very bad crime' is the definition.
I know nothing about this answer so I cannot judge whether it can be defined by this definition.

'cease-fire no ufos but a very bad crime' is the wordplay.
'cease-fire no ufos' anagrams to 'A SERIOUS OFFENCE'.
But, I am unsure how the anagram is indicated.

Can you help me to learn more?

I've seen this clue in the Sydney Morning Herald.
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