Gang of Nazis protected by American author (5)
I believe the answer is:
posse
'gang' is the definition.
(I've seen this before)
'nazis protected by american author' is the wordplay.
'nazis' becomes 'ss' (I am not sure about this - if you are sure you should believe this answer much more).
'protected by' is an insertion indicator.
'american author' becomes 'Poe' (Edgar Allan Poe).
'ss' going inside 'poe' is 'POSSE'.
'of' is the link.
Can you help me to learn more?
(Other definitions for posse that I've seen before include "Sheriff's team" , "Group temporarily established for some purpose" , "Sheriff's party" , "Group formed by sheriff" , "Group of friends together" .)