Crux (4)
'crux' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for core that I've seen before include "Crux" , "The centre part, as of an apple" , "Centre, heart" , "Nucleus" , "Kernel" .)
'crux' is the definition.
(gist can mean the essence or crux of something)
This is all the clue.
(Other definitions for gist that I've seen before include "The substance of a text" , "Central idea" , "Core meaning" , "Main points" , "Drift" .)
'crux' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for pith that I've seen before include "Spongy tissue lining rinds of oranges, or the essential part" , "hats may be made of this" , "Inner skin of citrus fruit" , "The white part of the orange" , "Inside skin of, say, orange" .)