Opening wine that goes with almost everything (6)
I believe the answer is:
portal
'opening' is the definition.
(type of opening or entrance)
'wine that goes with almost everything' is the wordplay.
'wine' becomes 'port' (port wine is a kind of wine).
'that goes with' means one lot of letters go next to another.
'almost' means to remove the last letter (almost the whole word is kept).
'everything' becomes 'all' (all things).
'all' with its final letter removed is 'al'.
'port'+'al'='PORTAL'
(Other definitions for portal that I've seen before include "Grand and imposing entrance" , "Gate, entrance" , "Grand sort of entrance." , "Special website bringing together information from diverse sources in a uniform way" , "An imposing door or gate" .)