Somewhat disheartened accountant getting sack (1,6)
I believe the answer is:
a trifle
'somewhat' is the definition.
(I've seen this before)
'disheartened accountant getting sack' is the wordplay.
'disheartened' means to remove the middle letters (the middle or heart is removed).
'getting' says to put letters next to each other.
'sack' becomes 'rifle' (both can mean to steal).
'accountant' with its centre removed is 'at'.
'at'+'rifle'='A TRIFLE'
(Other definitions for a trifle that I've seen before include "somewhat" , "Slightly" .)