Former cubicle on hospital department cracking (9)
I believe the answer is:
excellent
'cracking' is the definition.
'former cubicle on hospital department' is the wordplay.
'former' becomes 'ex' (prefix meaning former or onetime).
'cubicle' becomes 'cell' (synonyms).
'on' says to put letters next to each other.
'hospital department' becomes 'ENT' (Ear, Nose and Throat department).
'ex'+'cell'+'ent'='EXCELLENT'
(Other definitions for excellent that I've seen before include "magic" , "Quite splendid, extremely good" , "Fine" , "brilliant" , "Admirable, first-rate" .)