Commentator is nasty about getting a student (7)
I believe the answer is:
analyst
'commentator' is the definition.
(I've seen this in another clue)
'nasty about getting a student' is the wordplay.
'about' indicates anagramming the letters.
'getting' is an insertion indicator.
'student' becomes 'L' (as in L-plates for learner drivers).
'nasty' anagrammed gives 'anyst'.
'a'+'l'='al'
'anyst' enclosing 'al' is 'ANALYST'.
'is' acts as a link.
(Other definitions for analyst that I've seen before include "One making detailed examination" , "one involved in breakdown" , "Scientific or technical worker" , "Examiner - psychiatrist" , "Practical chemist" .)