Threatening, in order to achieve command (10)
I believe the answer is:
forbidding
'threatening in order' is the definition.
'forbidding' can be an answer for 'threatening' (thesaurus). I'm not certain of the 'in order' bit.
'achieve command' is the wordplay.
'achieve' becomes 'for' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'command' becomes 'bidding' (synonyms).
'for'+'bidding'='FORBIDDING'
'to' acts as a link.
Can you help me to learn more?
(Other definitions for forbidding that I've seen before include "Banning" , "Grim" , "sinister" , "Ominous" .)