The most common and most likely answer to this crossword clue is the 10 letter word QUADRILLES
I've seen this crossword clue in Independent
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Buddy explains!
The straight part
We know that "I’ll denote, for a start, square dances?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case i’ll denote, for a start, square dances? = quadrilles.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.
Crossword Answer definitions
QUADRILLES noun- A dance originating in the mid-1700s with four couples forming a square, rather much like the modern square dance.
- The music for this dance.
- A Spanish trick-taking card game from the 1700s played with a 40-card deck.
- A choreographed dressage ride, commonly performed to music, with a minimum of four horses.
- Quadrille ruled graph paper, quad paper.