Gloomy clutching one's small sack (9)
I believe the answer is:
dismissal
'sack' is the definition.
(sacking is dismissal from one's job)
'gloomy clutching one's small' is the wordplay.
'gloomy' becomes 'dismal' (synonyms).
'clutching' means one lot of letters goes inside another.
'one's' becomes 'I's' (Roman numeral).
'small' becomes 's' (abbreviation - e.g. clothes size).
'is'+'s'='iss'
'dismal' going around 'iss' is 'DISMISSAL'.
(Other definitions for dismissal that I've seen before include "Rejection" , "Process of being sent away" , "removal from office" , "Sacking; end of innings" , "getting cards?" .)