I catch visiting duke inside — pretty sick (2,1,3,3)

I believe the answer is:

in a bad way

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

'sick' is the definition.
(thesaurus)

I cannot understand how the rest of the clue works.

(Other definitions for in a bad way that I've seen before include "Unwell" , "Suffering" , "how the incompetent perform?" , "Seedy" , "Seriously ill" .)

I've seen this clue in The Guardian.

Want a hint initially instead of a full solution? Install my app