Host swallowing wine gum (6)
I believe the answer is:
mastic
'gum' is the definition.
(mastic is a resin also called arabian gum)
'host swallowing wine' is the wordplay.
'host' becomes 'mc' (short for master of ceremonies).
'swallowing' means one lot of letters goes inside another.
'wine' becomes 'asti' (Italian wine).
'mc' going around 'asti' is 'MASTIC'.
(Other definitions for mastic that I've seen before include "Mac, sit and produce a gum resin" , "Putty-like cement used as adhesive or filler" , "liquor" , "Aromatic resin used to make varnish" , "Substance applied to joints" .)