Arranged matter over hospital department's handling (9)
I believe the answer is:
treatment
'handling' is the definition.
('treatment' can be a synonym of 'handling')
'arranged matter over hospital department's' is the wordplay.
'arranged' indicates an anagram.
'over' says to put letters next to each other.
'hospital department' becomes 'ent'.
'matter' anagrammed gives 'treatm'.
'treatm'+'ent'='TREATMENT'
(Other definitions for treatment that I've seen before include "Application of remedy" , "course of drugs" , "Discussion" , "The handling or management of something" , "Management of something, illness say" .)