What does the cryptic crossword clue "It’s at risk when making phone call (2,3,4)" mean?

The definition is "It’s at risk when making phone call". The wordplay uses a double definition. Double definition The answer is ONTHELINE.

It’s at risk when making phone call (2,3,4)

Guardian Cryptic #29665 | 11 Across | 2025-04-10 flower