Pardon a brother that accepts shelter (7)
I believe the answer is:
amnesty
'pardon' is the definition.
(I know that pardon can be written as amnesty)
'a brother that accepts shelter' is the wordplay.
'brother' becomes 'my' (both are expressions of shock).
'that accepts' indicates putting letters inside.
'shelter' becomes 'nest' (I've seen this in other clues).
'my' placed around 'nest' is 'mnesty'.
'a'+'mnesty'='AMNESTY'
(Other definitions for amnesty that I've seen before include "A general pardon as for rebels (7)" , "General pardon for crimes against the state" , "General pardon, usually political" , "When law is suspended" , "suspension of law" .)