Passing comment? Nothing had an effect (4)
I believe the answer is:
obit
'passing comment?' is the definition.
(obituary, report on someone's passing)
'nothing had an effect' is the wordplay.
'nothing' becomes 'O' (O resembles 0).
'had an effect' becomes 'bit' (bite can mean to take effect).
'o'+'bit'='OBIT'
(Other definitions for obit that I've seen before include "Death notice (colloq.)" , "funeral service" , "Memorial biography (abbr)" , "Commemoration of a death (abbr)" , "newspaper article" .)