The most common and most likely answer to this crossword clue is the 5 letter word QUOIN
Q
U
O
I
N
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The straight part
We know that "Wedge" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case wedge = quoin.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 QUOIN mean?
QUOIN noun- Any of the corner building blocks of a building, usually larger or more ornate than the surrounding blocks.
- The keystone of an arch.
- A metal wedge which fits into the space between the type and the edge of a chase, and is tightened to fix the metal type in place.
- A form of wedge used to prevent casks from moving
- A wedge of wood or iron put under the breech of heavy guns or the muzzle of siege-mortars to raise them to the proper level.
- To wedge or steady with quoins.