Back master to prepare for battle again (5)
I believe the answer is:
rearm
'prepare for battle again' is the definition.
I can't tell whether this defines the answer.
'back master' is the wordplay.
'back' becomes 'rear' (something's rear is its back).
'master' becomes 'm'.
'rear'+'m'='REARM'
'to' is the link.
Can you help me to learn more?
(Other definitions for rearm that I've seen before include "prepare to fight again" , "Increase weaponry" , "Take weapons again" , "Provide with a new supply of weapons" , "Equip with new or better weapons" .)