Minutes before oral, damaged back tooth (5)
I believe the answer is:
molar
'back tooth' is the definition.
(I've seen this before)
'minutes before oral damaged' is the wordplay.
'minutes' becomes 'm'.
'before' is a charade indicator (letters next to each other).
'damaged' indicates anagramming the letters.
'oral' with letters rearranged gives 'olar'.
'm'+'olar'='MOLAR'
(Other definitions for molar that I've seen before include "Dealing with masses" , "Broad-crowned tooth" , "Large tooth" , "that could be capped" , "part of the daily grind" .)