Nurse dispenses this around one - it's kept in hospital cupboard (4)
I believe the answer is:
talc
'nurse dispenses this around one it's kept' is the definition.
The definition suggests a singular noun which matches the answer.
'in hospital cupboard' is the wordplay.
'in' indicates a hidden word.
'TALC' is hidden within 'hospital cupboard'.
(Other definitions for talc that I've seen before include "Soft stuff" , "Bathroom powder (abbr)" , "Mineral used as a toiletry" , "I may dust" , "Fine powder" .)