The most common and most likely answer to this crossword clue is the 6 letter word MULLER
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More clues leading to the result MULLER
Buddy explains!

The straight part
We know that "One producing e.g. glühwein/wallop" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case one producing e.g. glühwein/wallop = muller.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does MULLER mean?
MULLER noun- One who, or that which, mulls.
- A grinding stone, held in the hand, used especially for preparing paints and powders.
- A vessel in which wine, etc., is mulled over a fire.
- To grind up into, or as if into, powder.
- A machine that mixes sand and clay for use in metal castings.
- To beat; to thrash (a person).
- To defeat or destroy utterly (as in a sport or competition).