"Crux" is unclued so can start with any letter rather than the alphabetical progression of the majority of the clues. It's not a particularly obvious phrase but the words themselves are very common ones.
The wordplay leads to an answer (13, 3 words), but presumably the entry - which does begin with an appropriate alphabetical letter - may not be 13, 3 words!?
It's unclear.
There's a 13 letter gap to fill.
I think the crux one is middle letter of editors + three letter synonym for cut with synonym for plot inside. It’s certainly driving me up the proverbial!