The most common and most likely answer to this crossword clue is the 11 letter word GALLOWGLASS
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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 GALLOWGLASS mean?
GALLOWGLASS noun- A mercenary warrior élite among Gaelic-Norse clans residing in the Western Isles of Scotland and Scottish Highlands from the mid 13th century to the end of the 16th century.