Type of filling (5)
I believe the answer is:
inlay
'type of filling' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for inlay that I've seen before include "Embedded decoration" , "Filling shaped to fit a tooth cavity" , "Mix images" , "Type of woodwork" , "Decoration of a surface by inserting wood, stone or metal" .)