Equip old man for battle in the last war (10)
I believe the answer is:
armageddon
'battle in the last war' is the definition.
'Armageddon' can be an answer for 'war' (I have seen 'Terrible war' mean 'armageddon' so perhaps 'war' could also mean 'armageddon'). I am unsure of the 'battle in the last' bit.
'equip old man' is the wordplay.
'equip' becomes 'arm' (arm can mean to equip someone with something).
'old' becomes 'aged' (similar in meaning).
'man' becomes 'Don' (Don is an example).
'arm'+'aged'+'don'='ARMAGEDDON'
'for' is the link.
Can you help me to learn more?
(Other definitions for armageddon that I've seen before include "large-scale conflict" , "Terrible war" , "battle missed" , "ultimate conflict" , "Apocalyptic battle" .)