Damage edge of gold filling and tooth (5)
I believe the answer is:
molar
'tooth' is the definition.
(I know that molar is a type of tooth)
'damage edge of gold filling' is the wordplay.
'damage' becomes 'mar' (to mar is to spoil or damage).
'edge of' says to hollow out the word (remove centre letters) (I've seen 'edges of' mean this).
'gold' becomes 'oil' (I have seen 'Black gold ' mean 'oil' so perhaps 'gold' could also mean 'oil').
'filling' indicates putting letters inside.
'oil' with its centre taken out is 'ol'.
'mar' enclosing 'ol' is 'MOLAR'.
'and' is the link.
(Other definitions for molar that I've seen before include "Chewer and grinder" , "Broad-crowned tooth" , "Dealing with masses" , "Type of tooth" , "part of the daily grind" .)