The most common and most likely answer to this crossword clue is the 7 plus 5 letter word HALLEYS COMET
I've seen this crossword clue in The Guardian
H
A
L
L
E
Y
S
C
O
M
E
T
Buddy explains!
The straight part
We know that "Ye shall possibly appear on time, around 2061" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case ye shall possibly appear on time, around 2061 = halleys comet.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.