Pinter's eccentric identification is fearless (8)
I believe the answer is:
intrepid
'is fearless' is the definition.
(synonyms)
'pinter's eccentric identification' is the wordplay.
'eccentric' indicates an anagram.
'identification' becomes 'ID' (abbreviation).
'pinter' anagrammed gives 'intrep'.
'intrep'+'id'='INTREPID'
(Other definitions for intrepid that I've seen before include "without fear" , "Afraid not" , "'Brave, dauntless (8)'" , "Unfearing" , "Undaunted" .)