Public commotion behind hospital is upsetting (12)
I believe the answer is:
overthrowing
'is upsetting' is the definition.
(upset can mean to overthrow or knock over)
'public commotion behind hospital' is the wordplay.
'public' becomes 'overt' (both can mean well-known or unconcealed).
'commotion' becomes 'rowing' (a row is a disturbance or commotion).
'behind' says to put letters next to each other.
'hospital' becomes 'H' (abbreviation for hospital).
'rowing' put after 'h' is 'hrowing'.
'overt'+'hrowing'='OVERTHROWING'
(Another definition for overthrowing that I've seen is " Removing from power".)