Military order read out (7)
I believe the answer is:
martial
'military' is the definition.
(similar in meaning)
'order read out' is the wordplay.
'order' becomes 'marshal' (marshal can mean to gather or order).
'read out' shows a homophone (sound like).
'marshal' is a homophone of 'MARTIAL'.
(Other definitions for martial that I've seen before include "Of war or the armed forces" , "Specialist in epigrams" , "associated with arts and law" , "relating to soldiers" , "Soldierly (arts?)" .)