tip-off

noun

(idiomatic) An obvious clue or indication. / (idiomatic) A report of suspicious behaviour, especially to an authority.

The mysterious note left at the crime scene was a tip-off to the identity of the killer.

意味（1）

(idiomatic) An obvious clue or indication.

The broken window and overturned plant pots were a tip-off that something was wrong.

意味（2）

(idiomatic) A report of suspicious behaviour, especially to an authority.

The police received a tip-off about a recent bank robbery.