Out of danger, if the telephone is incapable of receiving calls (3,3,4)
I believe the answer is:
off the hook
'out' is the definition.
Both the answer and definition are adjectives. Perhaps there's a link between them I don't understand?
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for off the hook that I've seen before include "Exculpated" , "Out of danger - freed of guilt" , "Close to the Dutch shore" , "Safe from further blame or obligation" , "near to Holland landmark?" .)