Discernment that’s visible? (7)
I believe the answer is:
insight
I believe this clue is a double definition.
'discernment' is the first definition.
(insight is a kind of discernment)
'visible?' is the second definition.
(thesaurus)
'that's' is the link.
(Other definitions for insight that I've seen before include "Visible" , "Ability to understand" , "Things I have understanding of" , "Grasp" , "Furniture from Princes Street for" .)