Hear silent order (6)
I believe the answer is:
listen
'hear' is the definition.
(I know that hear can be written as listen)
'silent order' is the wordplay.
'order' is an anagram indicator.
'silent' is an anagram of 'LISTEN'.
(Other definitions for listen that I've seen before include "Hark!" , "Attend (to a sound)" , "Harken" , "Lend an ear (6)" , "Make an effort to hear" .)