I mention going wrong very quickly (2,2,4)
I believe the answer is:
in no time
'very quickly' is the definition.
(I've seen this before)
'i mention going wrong' is the wordplay.
'going wrong' indicates anagramming the letters.
'mention' anagrammed gives 'nnotime'.
'i'+'nnotime'='IN NO TIME'
(Other definitions for in no time that I've seen before include "Immediately" , "Very rapidly, hardly measurable" , "Swiftly" , "Without delay, too quick to measure" , "Very rapidly - but sounds impossible?" .)