Kind soldiers in street (4)
I believe the answer is:
sort
'kind' is the definition.
(I know that kind can be written as sort)
'soldiers in street' is the wordplay.
'soldiers' becomes 'or' (Other Ranks).
'in' indicates putting letters inside.
'street' becomes 'st' (abbreviation).
'or' put into 'st' is 'SORT'.
(Other definitions for sort that I've seen before include "Tidy" , "Arrange systematically" , "Work out" , "class" , "Group" .)