Giving notice eating irons must be replaced (11)
I believe the answer is:
resignation
'giving notice' is the definition.
(resigning is giving in one's notice)
'eating irons must be replaced' is the wordplay.
'must be replaced' indicates anagramming the letters.
'eating'+'irons'='eatingirons'
'eatingirons' with letters rearranged gives 'RESIGNATION'.
(Other definitions for resignation that I've seen before include "surrender" , "Giving up job" , "Calm acceptance" , "Acceptance of the inevitable" , "acquiescence" .)