The most common and most likely answer to this crossword clue is the 2 letter word OK
I've seen this crossword clue in The Guardian
O
K
More clues leading to the result OK
Buddy explains!
The straight part
We know that "Just" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case just = ok.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 OK mean?
OK adjective- All right, permitted.
- Satisfactory, reasonably good; not exceptional.
- In good health or a good emotional state.