It's when everything began going wrong there today (3,4,3)
I believe the answer is:
the year dot
'it's when everything began' is the definition.
(the year dot means the beginning of time)
'going wrong there today' is the wordplay.
'going wrong' is an anagram indicator.
'there'+'today'='theretoday'
'theretoday' is an anagram of 'THE YEAR DOT'.
(Other definitions for the year dot that I've seen before include "The beginning of time (colloq.)" , "As long ago as can be remembered" , "A very long time ago" , "right at the start" , "date, one imagines" .)