Crossword Genius

Expert witness starts off with impudence (8)

Ross

I believe the answer is:

pertness

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

'impudence' is the definition.
(thesaurus)

I don't understand how the rest of the clue works.

Can you help me to learn more?

(Another definition for pertness that I've seen is " Presents (anag)".)

Want a hint initially instead of a full solution? Install my app