Trap I've prepared for soldier ... (7)
I believe the answer is:
private
'for soldier' is the definition.
(private is a type of soldier)
'trap i've prepared' is the wordplay.
'prepared' is an anagram indicator.
'trap'+'ive'='trapive'
'trapive' is an anagram of 'PRIVATE'.
(Other definitions for private that I've seen before include "Whispered" , "Soldier; personal" , "Personal or secret" , "Rank, concealed" , "Lowest rank in the army" .)