Replaced nurse felt bitter (9)
I believe the answer is:
resentful
'bitter' is the definition.
(synonyms)
'replaced nurse felt' is the wordplay.
'replaced' indicates anagramming the letters.
'nurse'+'felt'='nursefelt'
'nursefelt' is an anagram of 'RESENTFUL'.
(Other definitions for resentful that I've seen before include "feeling sore" , "Feeling indignation" , "Grudging" , "Feeling hostile because of injury" , "Disgruntled" .)