"Yes, of course" (9)

I believe the answer is:

certainly

This clue is a double definition.

'yes' is the first definition.
(I've seen this in another clue)

'of course' is the second definition.
(I've seen this in another clue)

(Other definitions for certainly that I've seen before include "Definitely, positively" , "Thirty seven [37D=WITHOUT FAIL]" , "By all means" , "Of course" , "Assuredly" .)

I've seen this clue in The New York Times.

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