Never reprehensible solvers' magazine now defunct (3,2,4,4)
I believe the answer is:
not on your life
'never' is the definition.
(phrase meaning 'never' or 'absolutely not')
'reprehensible solvers' magazine now defunct' is the wordplay.
I cannot really see how this works, but
'solvers'' could be 'you' (the person or people solving the crossword) and 'you' is present in the answer.
'magazine' could be 'life' (former US magazine) and 'life' is found within the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for not on your life that I've seen before include "Under no circumstances" , "Expression of strong denial" , "On no account whatsoever" , "Never! (colloq.)" , "No way!" .)