An inventive criminal? (6)

'an inventive criminal?' is the definition.
The answer and definition can be both people as well as being singular nouns.
Perhaps you can see a link between them that I don't see?

'an inventive criminal?' is the wordplay.
I cannot really understand how this works, but
'an' could be 'i' (Roman numeral for one) and 'i' is present in the answer.
'criminal?' could be 'con' (abbreviation for 'convict') and 'con' is found in the leftover letters.
The remaining letters 'er' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...

Can you help me to learn more?