Mark of disgrace upset American soldiers? About time (6)
I believe the answer is:
stigma
'mark of disgrace' is the definition.
(I've seen this before)
'upset american soldiers? about time' is the wordplay.
'upset' says the letters should be written backwards.
'american' becomes 'am' (abbreviation in some contexts).
'soldiers?' becomes 'gis' (I've seen this in other clues**).
'about' means one lot of letters goes inside another.
'time' becomes 't'.
'am'+'gis'='amgis'
'amgis' going around 't' is 'amgits'.
'amgits' reversed gives 'STIGMA'.
(Other definitions for stigma that I've seen before include "Badge of shame" , "evidence of nastiness?" , "A stain as on character" , "Mark of dishonour" , "Sign of disgrace" .)