Soldier by border town in Ireland (6)
I believe the answer is:
antrim
'town in ireland' is the definition.
(I've seen this before)
'soldier by border' is the wordplay.
'soldier' becomes 'ant' (soldier is a type of ant).
'by' says to put letters next to each other.
'border' becomes 'rim' (both can mean an edge).
'ant'+'rim'='ANTRIM'
(Other definitions for antrim that I've seen before include "NI town" , "County of northeast Ireland" , "Irish county of musically green glens" , "Part of Ireland" , "town in Ireland" .)