Gloomy about - is the second sacking (9)
I believe the answer is:
dismissal
'sacking' is the definition.
(I know that sacking can be written as dismissal)
'gloomy about is the second' is the wordplay.
'gloomy' becomes 'dismal' (synonyms).
'about' indicates putting letters inside.
'the second' becomes 's' (common abbreviation).
'is'+'s'='iss'
'dismal' enclosing 'iss' is 'DISMISSAL'.
(Other definitions for dismissal that I've seen before include "Removal from employment" , "Discharge" , "sending off" , "Sacking; end of innings" , "brush-off" .)