Cryptic crossword clue
Gun once needing revolutionary advance to support unprotected brands 8

The most common and most likely answer to this crossword clue is the 8 letter word ARQUEBUS

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Buddy explains!

The straight part
We know that "Gun once" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case gun once = arquebus.
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 ARQUEBUS mean?

ARQUEBUS verb
  1. To shoot with an arquebus.
ARQUEBUS noun
  1. An obsolete matchlock firearm.
  2. A portable gun, varying in size from a small cannon to a musket. When used in the field it was supported upon a tripod or trestle.

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