Crooked furniture used regularly (6)
I believe the answer is:
untrue
'crooked' is the definition.
Both the answer and definition are adjectives. Perhaps there's an association between them I don't understand?
'furniture used regularly' is the wordplay.
'regularly' means one should take alternating letters (regularly take one letter, leave next etc.).
'furniture'+'used'='furnitureused'
The alternating letters of 'furnitureused' are 'UNTRUE'.
Can you help me to learn more?
(Other definitions for untrue that I've seen before include "Not loyal" , "Not factual or honest" , "Sleeping around" , "Not in accordance with the facts" , "Not faithful" .)