Swathe (7)
'swathe' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for envelop that I've seen before include "Enclose" , "Give all-round cover" , "Hide" , "Compass" , "Surround completely" .)
(Other definitions for bandage that I've seen before include "Wound binding" , "Bind (a wound)" , "Material for wound or injury" , "medical cover" , "Wrapping for wound" .)