Sweep about to be admitted to hospital (4)
I believe the answer is:
scan
'sweep' is the definition.
(thesaurus)
'about to be admitted to hospital' is the wordplay.
'about' becomes 'c' (abbreviation for 'circa').
'to be admitted to' means one lot of letters goes inside another.
'hospital' becomes 'san' (I've seen this before).
'c' going within 'san' is 'SCAN'.
(Other definitions for scan that I've seen before include "Read hastily" , "Hercule ---, detective" , "Glance negligently at" , "Glance at quickly rather than thoroughly" , "Examine data" .)