Hospital workers harbour grudges, ultimately (6)
I believe the answer is:
nurses
'hospital workers' is the definition.
(I've seen this before)
'harbour grudges ultimately' is the wordplay.
'harbour' becomes 'nurse' (I've seen this before).
'ultimately' indicates one should take the final letters.
The last letter of 'grudges' is 's'.
'nurse'+'s'='NURSES'
(Other definitions for nurses that I've seen before include "preserves" , "Takes care of the sick" , "They take care of the sick" , "Cares for the sick." , "Hospital workers" .)