Unaware or forgetful (9)
I believe the answer is:
oblivious
I believe this clue is a double definition.
'unaware' is the first definition.
(similar in meaning)
'forgetful' is the second definition.
(I know that forgetful can be written as oblivious)
(Other definitions for oblivious that I've seen before include "Forgetful; unaware" , "Unconscious" , "Absent-mindedly unaware" , "Blind (to)" , "Apt to forget" .)