Outrage about broken arm being national emblem (8)
I believe the answer is:
shamrock
'national emblem' is the definition.
(I've seen this before)
'outrage about broken arm' is the wordplay.
'outrage' becomes 'shock' (synonyms).
'about' means one lot of letters goes inside another.
'broken' indicates an anagram.
'arm' is an anagram of 'amr'.
'shock' going around 'amr' is 'SHAMROCK'.
'being' acts as a link.
(Other definitions for shamrock that I've seen before include "Irish national symbol" , "Irish national emblem" , "Clover leaf" , "Clover-like plant" , "symbolic of Ireland" .)