The most common and most likely answer to this crossword clue is the 2 plus 3 plus 4 letter word AT ONE TIME
I've seen this crossword clue in The Times
A
T
O
N
E
T
I
M
E
More clues leading to the result AT ONE TIME
- A style issue that’s been raised previously
- Once together on paper, briefly
- Make good porridge together
- Make amends with item reordered previously
- Make amends for issue arising previously
- Previously in unison
- Pay for return of issue once
- Pay for putting up shed years ago
- Formerly together
- Together years ago?
Buddy explains!

The straight part
We know that "previously" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case previously = at one time.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.