Stars and Stripes, say, on wine jug (6)
I believe the answer is:
flagon
'wine jug' is the definition.
(I've seen this before)
'stars and stripes say on' is the wordplay.
'stars and stripes say' becomes 'flag' (stars and stripes is a kind of flag).
'flag'+'on'='FLAGON'
(Other definitions for flagon that I've seen before include "Wine jug" , "Large vessel with a handle and spout" , "Drinking vessel" , "Large bottle for alcohol" , "Snow White companion" .)