Complete veneer (6)
I believe the answer is:
finish
I believe this clue is a double definition.
'complete' is the first definition.
(I know that complete can be written as finish)
'veneer' is the second definition.
(thesaurus)
(Other definitions for finish that I've seen before include "Perfect" , "surface texture" , "End or terminus" , "Conclude, wind up" , "Treatment of surface" .)