She fires revolting Piers Morgan at last (6)

I believe the answer is:
sniper
'she fires revolting piers morgan at last' is the definition.
I can't judge whether this defines the answer.
'revolting piers morgan at last' is the wordplay.
'revolting' indicates anagramming the letters.
'at last' indicates one should take the final letters.
The final letter of 'morgan' is 'n'.
'piers'+'n'='piersn'
'piersn' is an anagram of 'SNIPER'.
Can you help me to learn more?
(Other definitions for sniper that I've seen before include "One who criticises" , "Hidden marksman" , "Single marksman in concealed place" , "one who takes pot from a safe place" , "Concealed sharpshooter" .)
