Manxman, for example, doesn't start defamation (7)

I believe the answer is:

slander

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

'defamation' is the definition.
(I know that defamation can be written as slander)

I don't understand the rest of the clue.

Can you help me to learn more?

(Other definitions for slander that I've seen before include "Sling mud at" , "False/malicious speech" , "muckraking!" , "Malicious speech" , "Calumny" .)

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