Letters delivered in the wrong place (8,7)
I believe the answer is:
spelling mistake
'letters delivered' is the definition.
I don't know anything about this answer so I cannot tell whether it can be defined by this definition.
'in the wrong place' is the wordplay.
I cannot really see how this works, but
'in' is present in the answer.
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is present in the answer.
'wrong' could be 'mis' (similar in meaning) and 'mis' is found in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for spelling mistake that I've seen before include "Harry Potter might make?" , "Error" .)