“Sinner” for “sinker”? I’m not sure — “singer”? Let me think (7)

I believe the answer is:

erratum

I'm a little stuck... Click here to teach me more about this clue!

'sinner for sinker?' is the definition.
I can't tell whether this defines the answer.

'i'm not sure singer? let me think' is the wordplay.
'i'm not sure' becomes 'er' (expression of hesitation).
'singer?' becomes 'rat' (both can mean an informant).
'let me think' becomes 'um' (expression of hesitation).
'er'+'rat'+'um'='ERRATUM'

Can you help me to learn more?

(Other definitions for erratum that I've seen before include "Printer's mistake" , "Faux pas" , "Printing mistake" , "gaffe" , "Typo" .)

I've seen this clue in The Times.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.