Couldn't remember after being brain-washed? (5,6)

'couldn't remember after being brain-washed?' is the definition.
I don't know anything about this answer so I can't tell whether it can be defined by this definition.

'couldn't remember after being brain-washed?' is the wordplay.
I cannot really understand how this works, but
'washed?' could be 'clean' ('clean' can be similar in meaning to 'washed') and 'clean' is found in the answer.
'couldn't remember' could be 'forgot' (I've seen this in another clue) and 'forgot' is found within the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).

Can you help me to learn more?