Time went quickly when discussing complaint (4,3)
I believe the answer is:
bird flu
'complaint' is the definition.
(I have seen 'Avian disease' mean 'bird flu' so perhaps 'disease' could also mean 'bird flu')
'time went quickly when discussing' is the wordplay.
'time' becomes 'bird' (both are slang for a prison sentence).
'went quickly' becomes 'flew' (the time flew by).
'when discussing' shows a homophone (sound like).
'flew' sounds like 'flu'.
'bird'+'flu'='BIRD FLU'
(Other definitions for bird flu that I've seen before include "Avian virus that can spread to humans" , "viral disease" , "Poultry virus that can spread to humans" , "Avian disease contractible by humans" .)