Mix up hospital department's viewpoint (8)
I believe the answer is:
entangle
'mix up' is the definition.
(thesaurus)
'hospital department's viewpoint' is the wordplay.
'hospital department' becomes 'ent'.
'viewpoint' becomes 'angle' (angle is a kind of viewpoint).
'ent'+'angle'='ENTANGLE'
(Other definitions for entangle that I've seen before include "Ensnare" , "Involve in complicated circumstances" , "Entwine into a confusing mass" , "Confuse" , "Make twisted" .)