Phone not working? It's cut-off point! (8)
I believe the answer is:
deadline
'cut-off point' is the definition.
(I've seen this before)
'phone not working?' is the wordplay.
I cannot quite see how this works, but
'not working?' could be 'dead' (I've seen this in another clue) and 'dead' is found in the answer.
The remaining letters 'line' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
'it's' acts as a link.
Can you help me to learn more?
(Other definitions for deadline that I've seen before include "Latest time for doing something" , "a writer may have to meet" , "Time by which journalist must file copy" , "Time for finishing" , "Target time" .)