Grunt about new and old wine left out in the cold (7)
I believe the answer is:
ignored
'left out in the cold' is the definition.
(I've seen this before)
'grunt about new and old wine' is the wordplay.
'grunt about' becomes 'ig' (I am not sure about this - if you are sure you should believe this answer much more).
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'and' is a charade indicator (letters next to each other).
'old' becomes 'o' (abbreviation).
'wine' becomes 'red' (red is a type of wine).
'ig'+'n'+'o'+'red'='IGNORED'
Can you help me to learn more?
(Other definitions for ignored that I've seen before include "Took no notice of" , "Snubbed" , "Failed to notice" , "Cut" , "Shunned" .)