Unintended eating from tins is back happening? Not at home (10)
I believe the answer is:
'unintended eating' is the definition.
(a 'snack accident')
'tins is back happening? not at home' is the wordplay.
I cannot really understand how this works, but
'happening?' could be 'accident' (accident is a kind of happening) and 'accident' is present in the answer.
This may be the basis of clue (or it may be nonsense).
'from' is the link.