Sublime joke grasped by academic in charge (8)
I believe the answer is:
majestic
'sublime' is the definition.
(thesaurus)
'joke grasped by academic in charge' is the wordplay.
'joke' becomes 'jest' ('jest' can be a synonym of 'joke').
'grasped by' is an insertion indicator (I've seen this in other clues).
'academic' becomes 'ma'.
'in charge' becomes 'ic'.
'ma'+'ic'='maic'
'jest' placed into 'maic' is 'MAJESTIC'.
(Other definitions for majestic that I've seen before include "Grand, impressive" , "August" , "Regal - stately" , "Regal, imperial" , "Of royal appearance or status" .)