Brief inspection of accounts: nothing sound (5)
I believe the answer is:
audio
'sound' is the definition.
(synonyms)
'brief inspection of accounts nothing' is the wordplay.
'brief' means to remove the last letter (a shorter or briefer version of the word).
'inspection of accounts' becomes 'audit' (inspection of financial accounts).
'nothing' becomes 'O' (looks like zero - 0).
'audit' with its last letter taken away is 'audi'.
'audi'+'o'='AUDIO'
(Other definitions for audio that I've seen before include "Prefix indicating sound or word" , "Relating to sound or hearing" , "Prefix indicating hearing or sound" , "Sound recording" , "Denoting sound" .)