The most common and most likely answer to this crossword clue is the 10 letter word FRIENDLIES
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Buddy explains!

The straight part
We know that "teammates" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case teammates = friendlies.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 FRIENDLIES mean?
FRIENDLIES noun- A game which is of no consequence in terms of ranking, betting etc.
- A person or entity on the same side in a conflict.