Arrive shortly with defenders outside army base (8)
I believe the answer is:
barracks
'arrive shortly' is the definition.
I can't judge whether this defines the answer.
'defenders outside army base' is the wordplay.
'defenders' becomes 'backs' (I've seen this before).
'outside' indicates putting letters inside.
'army base' becomes 'arr' (I am not sure about this - if you are sure you should believe this answer much more).
'backs' going around 'arr' is 'BARRACKS'.
'with' is the link.
Can you help me to learn more?
(Other definitions for barracks that I've seen before include "Cheers ironically" , "For the rest of the men" , "Military quarters" , "Audibly disapproves of" , "private housing" .)