Military order bad food to be given to sick mares (5,4)
I believe the answer is:
slope arms
'military order bad' is the definition.
I don't know anything about this answer so I can't tell whether this works.
'food to be given to sick mares' is the wordplay.
'food' becomes 'slop' (slop is a kind of food).
'to be given to' indicates putting letters inside.
'sick' indicates anagramming the letters.
'mares' is an anagram of 'earms'.
'slop' inserted into 'earms' is 'SLOPE ARMS'.
Can you help me to learn more?
(Other definitions for slope arms that I've seen before include "military command" , "Put rifle on shoulder" , "Inclination members" .)