Prepare for another war (5)
I believe the answer is:
rearm
'prepare for another war' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for rearm that I've seen before include "Hand new weapons" , "Provide with a new supply of weapons" , "fit again" , "Equip with new or better weapons" , "Acquire new or better weapons" .)