The most common and most likely answer to this crossword clue is the 6 letter word QUAHOG
I've seen this crossword clue in The Times
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More clues leading to the result QUAHOG
Buddy explains!
The straight part
We know that "this shellfish may be eaten" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case this shellfish may be eaten = quahog.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 QUAHOG mean?
QUAHOG noun- An edible clam with a hard shell found along the Atlantic Coast of North America, from species Mercenaria mercenaria, formerly Venus mercenaria.
- A similar edible clam found along coasts around the North Atlantic, generally in deeper waters, the ocean quahog, black quahog, mahogany clam or Icelandic cyprine, Arctica islandica
- To dig for quahogs.