Soldiers organise line in conflict (12)
I believe the answer is:
legionnaires
'soldiers' is the definition.
(legionnaire is a kind of soldier)
'organise line in conflict' is the wordplay.
'in conflict' indicates anagramming the letters (I've seen this in other clues).
'organise'+'line'='organiseline'
'organiseline' anagrammed gives 'LEGIONNAIRES'.
(Other definitions for legionnaires that I've seen before include "troops" , "Servicemen" , "French soldiers" .)