Culmination, perfection (4)
I believe the answer is:
acme
I believe this clue is a double definition.
'culmination' is the first definition.
(I've seen this in another clue)
'perfection' is the second definition.
(thesaurus)
(Other definitions for acme that I've seen before include "Highest point of excellence or achievement" , "Came awkwardly to the highest point" , "high peak" , "Summit - maximum" , "Height of excellence" .)