How a card-sharp's cards differ from others? (8)

I believe the answer is:

markedly

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

'how' is the definition.
Both the definition and answer are adverbs. Perhaps they are linked in a way I don't understand?

I cannot understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for markedly that I've seen before include "In a clearly noticeable manner" , "Prominently, distinctly" .)

I've seen this clue in the Evening Standard.

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.