Gunmen invading eatery that stocks wine (6)
I believe the answer is:
carafe
'that stocks wine' is the definition.
(flask for serving wine)
'gunmen invading eatery' is the wordplay.
'gunmen' becomes 'RA' (Royal Artillery).
'invading' indicates putting letters inside.
'eatery' becomes 'cafe' (type of eatery).
'ra' going within 'cafe' is 'CARAFE'.
(Other definitions for carafe that I've seen before include "Wine is decanted into it" , "Decanter" , "Wine, water, jug" , "keeper of wine" , "Wide-necked bottle for the table" .)