Give more weapons back — one thousand (5)
I believe the answer is:
rearm
'give more weapons' is the definition.
'back one thousand' is the wordplay.
'back' becomes 'rear' (synonyms).
'one thousand' becomes 'm' (synonyms).
'rear'+'m'='REARM'
(Other definitions for rearm that I've seen before include "prepare to fight again" , "Take weapons again" , "fit again" , "Up the military budget?" , "Provide new weaponry" .)