Substance, general meaning (4)
I believe the answer is:
This clue is a double definition.
'substance' is the first definition.
(I know that substance can be written as gist)
'general meaning' is the second definition.
(I've seen this before)
(Other definitions for gist that I've seen before include "Essence; meaning" , "The substance of a text" , "Essential point or meaning of, say, the matter" , "Main idea, kernel of matter" , "Drift" .)