School's principal asking about covering last of specific dismissals (8)

'dismissals' is the definition.
('sacking' can be a synonym of 'dismissal')

'school's principal asking about covering last of specific' is the wordplay.
'principal' indicates taking the first letters.
'about' indicates anagramming the letters.
'covering' is an insertion indicator.
'last of' indicates one should take the final letters.
The initial letter of 'schools' is 's'.
The last letter of 'specific' is 'c'.
'asking' is an anagram of 'akings'.
'akings' going around 'c' is 'ackings'.
's'+'ackings'='SACKINGS'