Crossword Genius

Teaching op, with surgery, describing disease (10)

Ross

I believe the answer is:

pathogenic

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

'surgery describing disease' is the definition.
I can't tell whether this defines the answer.

'teaching op' is the wordplay.
'teaching op' anagrams to 'PATHOGENIC'.
However, I'm not sure how this is indicated.

'with' is the link.

Can you help me to learn more?

(Another definition for pathogenic that I've seen is " Causing disease".)

I've seen this clue in The Times.
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