Prepared, once more, for the day shift (5)
I believe the answer is:
ready
'prepared' is the definition.
(similar in meaning)
'once more for the day shift' is the wordplay.
'once more' becomes 're' (prefix in words like 're-emerge' or 're-enter').
'for' says to put letters next to each other.
'shift' indicates an anagram.
'day' anagrammed gives 'ady'.
're'+'ady'='READY'
(Other definitions for ready that I've seen before include "Primed" , "At hand" , "Prepare < dough" , "Willing (to do something), prepare" , "Prepared, willing" .)