Contains nuts, OK (8)
I believe the answer is:
sanction
'ok' is the definition.
('sanction' can be a synonym of 'ok')
'contains nuts' is the wordplay.
'nuts' indicates an anagram (nuts can mean crazy).
'contains' is an anagram of 'SANCTION'.
(Other definitions for sanction that I've seen before include "Go-ahead" , "Agree to - penalty" , "Confirm" , "Permit - punishment for breach of treaty" , "Threatened penalty; official permission" .)