Alec's chaotic graduation (5)
I believe the answer is:
scale
'graduation' is the definition.
(thesaurus)
'alec's chaotic' is the wordplay.
'chaotic' indicates anagramming the letters.
'alecs' with letters rearranged gives 'SCALE'.
(Other definitions for scale that I've seen before include "Climb; overlapping plate" , "Horny plate; balance" , "Go up" , "Size ratio; skin flake" , "Group of notes in ascending or descending order" .)