Letter opener chopped up dead seers (9)
I believe the answer is:
addressee
'letter opener' is the definition.
'chopped up dead seers' is the wordplay.
'chopped up' indicates an anagram.
'dead'+'seers'='deadseers'
'deadseers' with letters rearranged gives 'ADDRESSEE'.
(Other definitions for addressee that I've seen before include "Person whose name is on the envelope" , "Intended recipient of letter" , "He's written to" , "The one to whom the message is sent" , "The person to whom letter is delivered" .)