Ring off (4,2)
I believe the answer is:
hang up
'ring off' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for hang up that I've seen before include "Put on peg; disconnect call" , "that makes one stop talking" , "End telephone conversation by replacing receiver" , "An emotional problem or inhibition - suspend it" , "Close call" .)