The most common and most likely answer to this crossword clue is the 6 letter word BEFORE
I've seen this crossword clue in The Sunday Telegraph
B
E
F
O
R
E
More clues leading to the result BEFORE
- Carried round keys in the past
- Prior to support closure of house
- Back in front
- In sight of fine men, one buzzing about
- Favour first of entrants in advance
- Prior to support leader in Eucharist
- Earlier prototype of the C5, say?
- Eastern female entertained by tedious person earlier
- Previously support European
- Live number heard earlier
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 = before.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 BEFORE mean?
BEFORE adverb- At an earlier time.
- In advance.
- At the front end.
- Earlier than (in time).
- In front of in space.
- In the presence of.
- Under consideration, judgment, authority of (someone).
- In store for, in the future of (someone).
- In front of, according to a formal system of ordering items.
- At a higher or greater position than, in a ranking.
- In advance of the time when.
- Rather or sooner than.