A tip-off from British intelligence led to his arrest and subsequent conviction.
: our tip to him would be to behave (1845+)
(also tip off) To give useful information or advice, esp advance information that gives an advantage of some sort: The room clerk tipped him/ Who tipped Larkin off? (1749+, variant 1891+)
[origin uncertain; perhaps fr the notion of tipping, that is, tilting something in someone's direction]