Reckless uprising trapping American soldier (6)
I believe the answer is:
hussar
'soldier' is the definition.
(hussar is a kind of soldier)
'reckless uprising trapping american' is the wordplay.
'reckless' becomes 'rash' ('rash' can be a synonym of 'reckless').
'uprising' shows that the letters should be reversed in order.
'trapping' indicates putting letters inside.
'american' becomes 'us'.
'rash' back-to-front is 'hsar'.
'hsar' placed around 'us' is 'HUSSAR'.
(Other definitions for hussar that I've seen before include "Hungarian soldier" , "Soldier in a light cavalry regiment" , "Light cavalryman" , "Cavalryman, originally Hungarian" , "one often up on a charge" .)