Had been a forger, one didn't let oneself forget (4,1,4)

'forger one didn't let oneself forget' is the definition.
I know nothing about this answer so I can't tell whether this works.

'had been a' is the wordplay.
I cannot quite see how this works, but
'had' could be 'made' ('make' can be a synonym of 'have') and 'made' is present in the answer.
'a' could be 'an' and 'an' is found within the answer.
This may be the basis of the clue (or it may be nonsense).

Can you help me to learn more?