The most common and most likely answer to this crossword clue is the 13 letter word ACCOUTREMENTS
I've seen this crossword clue in The Daily Telegraph
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More clues leading to the result ACCOUTREMENTS
Buddy explains!

The straight part
We know that "Equipment" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case equipment = accoutrements.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 ACCOUTREMENTS mean?
ACCOUTREMENTS noun- The act of accoutering.
- An article of clothing or equipment, in particular when used as an accessory.
- Apparatus needed for a task or journey.
- Equipment other than weapons and uniform.
- Trappings.
- An identifying yet superficial characteristic.