Fine surface layer (6)
(Other definitions for patina that I've seen before include "Surface shine" , "Developing surface film; sheen" , "Surface coating that comes with age" , "Sheen acquired from constant handling" , "Surface film formed by age" .)
(Other definitions for veneer that I've seen before include "Superficial appearance" , "'e never (anag.)" , "Thin wooden covering" , "Thin skin on surface" , "Superficial coating" .)