Pardon, overlook (6)
I believe the answer is:
excuse
I believe this is a double definition.
'pardon' is the first definition.
(synonyms)
'overlook' is the second definition.
(thesaurus)
(Other definitions for excuse that I've seen before include "Allow to be released from a duty" , "Free - apology" , "Defence of offensive behaviour" , "Pardon or justify" , "Release (from a duty)" .)