New member of the family swaddled in backstreet pod arrangement (7)
I believe the answer is:
adoptee
'new member of the family swaddled' is the definition.
I don't know anything about this answer so I cannot judge whether it can be defined by this definition.
'in backstreet pod arrangement' is the wordplay.
'in' means one lot of letters goes inside another.
'backstreet' becomes 'atee' (I can't justify this - if you can you should believe this answer much more).
'arrangement' indicates an anagram.
'pod' is an anagram of 'dop'.
'atee' enclosing 'dop' is 'ADOPTEE'.
Can you help me to learn more?
(Other definitions for adoptee that I've seen before include "Child taken on by another family" , "one's taken into the family" , "One taken on by new parents" , "one who's left home" .)