Damage seen around most of ancient tooth (5)
I believe the answer is:
molar
'tooth' is the definition.
(I know that molar is a type of tooth)
'damage seen around most of ancient' is the wordplay.
'damage' becomes 'mar' (to mar is to spoil or damage).
'seen around' indicates putting letters inside.
'most of' means to remove the last letter.
'ancient' becomes 'old' (similar in meaning).
'old' with its final letter taken off is 'ol'.
'mar' going around 'ol' is 'MOLAR'.
(Other definitions for molar that I've seen before include "Broad-crowned tooth" , "that could be capped" , "Chewer and grinder" , "of ivory, perhaps" , "Moral (anag.)" .)