Insight (9)
'insight' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for acumen that I've seen before include "Mental keenness" , "Penetrating insight" , "Awareness" , "Gumption" , "'Keenness, depth of perception (6)'" .)
'insight' is the definition.
(thesaurus)
This is all the clue.
(Other definitions for intuition that I've seen before include "Hunch" , "Suspicion" , "women are known for it" , "An indefinable knowledge" , "Unconscious understanding" .)