End call, engagement being cancelled? (4,3)
I believe the answer is:
ring off
'end call' is the definition.
(to ring off is to hang up a phone call)
'engagement being cancelled?' is the wordplay.
'engagement being' becomes 'ring' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'cancelled?' becomes 'off' (similar in meaning).
'ring'+'off'='RING OFF'
(Other definitions for ring off that I've seen before include "Slam down phone" , "End a phone call" , "Terminate a call" , "Finish speaking" , "Put the phone down" .)