Covering the patient (4)
I believe the answer is:
case
I believe this is a double definition.
'covering' is the first definition.
(case is a kind of covering)
'patient' is the second definition.
(synonyms)
'the' acts as a link.
(Other definitions for case that I've seen before include "Box or outer covering" , "Reconnoitre" , "Wine buyer's basic quantity" , "Instance - container" , "Outer shell" .)