Main point (4)
'main point' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for crux that I've seen before include "brain-teaser!" , "Core" , "Baffling problem" , "Decisive, baffling, point" , "Most important aspect" .)
'main point' is the definition.
(the main point or meaning of something)
This is the entire clue.
(Other definitions for gist that I've seen before include "Main points" , "Real point or substance" , "Substance of an argument" , "Essence; meaning" , "Essential idea" .)