Auditor's signed tissue used in transfer (9)

I believe the answer is:

autograft

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

'transfer' is the definition.
Both the definition and answer are singular nouns.
Maybe you can see an association between them that I can't see?

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

I've seen this clue in The Independent.

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.