The most common and most likely answer to this crossword clue is the 11 letter word CANTILEVERS
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Buddy explains!

The straight part
We know that "Beams" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case beams = cantilevers.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 CANTILEVERS mean?
CANTILEVERS noun- A beam anchored at one end and projecting into space, such as a long bracket projecting from a wall to support a balcony.
- A beam anchored at one end and used as a lever within a microelectromechanical system.
- A technique, similar to the spread eagle, in which the skater travels along a deep edge with knees bent and bends their back backwards, parallel to the ice.