Scottish food given by witch to American soldiers (6)
I believe the answer is:
haggis
'scottish food' is the definition.
(haggis is a Scottish dish)
'by witch to american soldiers' is the wordplay.
'by' means one lot of letters go next to another.
'witch' becomes 'hag' (synonyms).
'to american soldiers' becomes 'GIs' (GI is an informal term for a US soldier).
'hag'+'gis' is 'HAGGIS'.
'given' is the link.
(Other definitions for haggis that I've seen before include "Dish served piping" , "Hi gags about traditional Scottish dish" , "Indonesian island; computer language" , "Robert Burns' "Great chieftain o' the puddin'-race"" , "traditional meal" .)