Disturbance in medical lecture (7)

I believe the answer is:

declaim

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

'lecture' is the definition.
(I've seen this before)

'disturbance in medical' is the wordplay.
'medical' can be anagrammed to 'DECLAIM'.
Though, I'm unsure how the anagram is indicated.

Can you help me to learn more?

(Other definitions for declaim that I've seen before include "Speak boldly" , "How orator will" , "Deliver (words) rhetorically" , "rant" , "Harangue" .)

I've seen this clue in The Telegraph.

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