NATO finally getting embassy to provide oversight (8)
I believe the answer is:
omission
'oversight' is the definition.
(omission is a kind of oversight)
'nato finally getting embassy' is the wordplay.
'finally' says to take the final letters.
'getting' is a charade indicator (letters next to each other).
'embassy' becomes 'mission' (I've seen this in other clues).
The last letter of 'nato' is 'o'.
'o'+'mission'='OMISSION'
'to provide' acts as a link.
(Other definitions for omission that I've seen before include "Gap" , "type of sin" , "Something left out or not done" , "lapse" , "Negligence" .)