Back in the past, you captured soldiers in time? (5)
I believe the answer is:
enemy
'soldiers in time?' is the definition.
'enemy' can be an answer for 'time?' (I've seen this before). I am unsure of the 'soldiers in' bit.
'back in the past you captured' is the wordplay.
'back' says the letters should be written in reverse.
'in the past' becomes 'men' (I can't justify this - if you can you should believe this answer much more).
'you' becomes 'ye' (historical version of 'you').
'captured' means one lot of letters goes inside another.
'men' going into 'ye' is 'ymene'.
'ymene' back-to-front is 'ENEMY'.
Can you help me to learn more?
(Other definitions for enemy that I've seen before include "Antagonist" , "is against us" , "Foe, adversary" , "other side (like 16)" , "Hostile person, foe" .)