Dull courtroom (6)

I believe the answer is:

wooden

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

I cannot understand how the rest of the clue works.

(Other definitions for wooden that I've seen before include "Lacking ease or grace, like a tree?" , "Ligneous" , "Awkward, like a tree?" , "acting badly" , "Stiff, awkward" .)

I've seen this clue in The Globe and Mail.

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