When I fail start - like that would ever happen (2,2)
I believe the answer is:
as if
'like that would ever happen' is the definition.
'as if' can be an answer for 'like' (I've seen this in another clue). I'm not certain of the remainder of the definition.
'when i fail start' is the wordplay.
'when' becomes 'as' (eg 'when I walked' means 'as I walked').
'start' suggests taking the first letters.
The first letter of 'fail' is 'f'.
'as'+'i'+'f'='AS-IF'
Can you help me to learn more?
(Other definitions for as if that I've seen before include "Yeah right!" , "You're joking!" , "a voice of doubt" , "Expression of incredulity" , "Or though" .)