Run United States hospital for career (4)
I believe the answer is:
rush
'for career' is the definition.
(career can mean to run or rush around)
'run united states hospital' is the wordplay.
'run' becomes 'r' (cricket abbreviation).
'united states' becomes 'US' (abbreviation for the United States).
'hospital' becomes 'h' (abbreviation for hospital on maps).
'r'+'us'+'h'='RUSH'
(Other definitions for rush that I've seen before include "Scurry" , "Liverpool footballer once" , "candle" , "plant developing on shore" , "Hurry to the river grass" .)