Note on hospital discharge (3)
I believe the answer is:
doh
'note' is the definition.
(alternative spelling of 'do' as in do re mi)
'on hospital discharge' is the wordplay.
'on' says to put letters next to each other.
'hospital' becomes 'h'.
'discharge' becomes 'do'.
'h' after 'do' is 'DOH'.
(Other definitions for doh that I've seen before include "Stupid me!" , "The note C" , "First note of major scale in music" , "whoops!" , "Note; exclamation" .)