The most common and most likely answer to this crossword clue is the 6 letter word SINGLY
I've seen this crossword clue in Independent
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More clues leading to the result SINGLY
Buddy explains!

The straight part
We know that "without companions?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case without companions? = singly.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 SINGLY mean?
SINGLY adverb- In a single or unaccompanied manner; without a companion.
- Individually; particularly; severally.
- Without partners, companions, or associates; single-handed.
- Honestly; sincerely; simply.
- Singularly; peculiarly.