Soldier on foot for the present (4)
I believe the answer is:
gift
'present' is the definition.
(I know that present can be written as gift)
'soldier on foot for the' is the wordplay.
'soldier' becomes 'gi' (term for US soldier).
'on' means one lot of letters go next to another (in a down clue, letters appear on others).
'foot' becomes 'f' (abbreviation).
'for' means one lot of letters go next to another.
'the' becomes 't' (the is pronounced as a 't' sound in some dialects).
'gi'+'f'+'t'='GIFT'
(Other definitions for gift that I've seen before include "A present or gratuity" , "[BOUNTY] ?" , "''Never look a .... horse in the mouth" , "Endowment" , "Special aptitude - present" .)