Powder in hospital cumulatively reduced (6)
I believe the answer is:
talcum
'powder' is the definition.
(talcum is a kind of powder)
'in hospital cumulatively reduced' is the wordplay.
'in' says the answer is hidden in the clue.
'TALCUM' is hidden in the letters of 'hospital cumulatively reduced'.
(Other definitions for talcum that I've seen before include "Scented toilet powder" , "Bathroom powder" , "Bathroom mineral" , "Standard body powder" , "Toilet powder which absorbs moisture" .)