Order round for military group (8)
I believe the answer is:
commando
'military group' is the definition.
(I know that commando is a type of military group)
'order round' is the wordplay.
'order' becomes 'command' (commanding is a kind of ordering).
'round' becomes 'o' (o is a circular letter).
'command'+'o'='COMMANDO'
'for' acts as a link.
(Other definitions for commando that I've seen before include "Army unit" , "Soldier trained for raiding" , "Shock troop unit" , "Kilt-wearer might go" , "Member of a special service military unit" .)