Cover render patch (7)
I believe the answer is:
plaster
I believe this clue is a triple definition!
'cover' is the first definition.
(plastering is a kind of covering)
'render' is the second definition.
(render is a coat of plaster)
'patch' is the third definition.
(patch can mean a plaster used to cover a wound)
(Other definitions for plaster that I've seen before include "Adhesive dressing" , "Medical dressing" , "Stucco" , "Stuff that sticks on ceilings or wounds" , "Material applied to walls" .)