Singer in hospital today (4)
I believe the answer is:
alto
'singer' is the definition.
(alto is a kind of singer)
'in hospital today' is the wordplay.
'in' says the answer is hidden in the clue.
'ALTO' is hidden in the letters of 'hospital today'.
(Other definitions for alto that I've seen before include "Highest male voice: lowest female voice" , "High male singing voice" , "Singer's hidden inside chemical toilet" , "Male singer" , "A singing voice or pitch" .)