Foolish king Danes totally unmasked (5)

I believe the answer is:

inane

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

'foolish' is the definition.
(similar in meaning)

I cannot understand how the remainder of the clue works.

(Other definitions for inane that I've seen before include "Without meaning or point" , "Silly or senseless" , "Stupid and silly" , "Lacking sense, silly" , "Silly, witless" .)

I've seen this clue in The Telegraph.

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