Crazy plan to restrain military assistant (6)
I believe the answer is:
madcap
'crazy' is the definition.
(I've seen this before)
'plan to restrain military assistant' is the wordplay.
'plan' becomes 'map' (plan can mean a map of something).
'to restrain' indicates putting letters inside.
'military assistant' becomes 'adc' (I can't explain this - if you can you should give a lot more credence to this answer).
'map' placed around 'adc' is 'MADCAP'.
Can you help me to learn more?
(Other definitions for madcap that I've seen before include "Silly" , "Rash person" , "Eccentric or reckless person" , "Foolhardy" , "Harum-scarum" .)