The most common and most likely answer to this crossword clue is the 7 plus 5 letter word DONKEYS YEARS
I've seen this crossword clue in The Guardian
D
O
N
K
E
Y
S
Y
E
A
R
S
More clues leading to the result DONKEYS YEARS
- Freakish dry season besets island for ages
- Opener in dry season bats for ages
- What Midas was given, extremely sensibly hidden, so long ago
- Animal’s attention held by hollowed out yams for ages
- Party approaches must protect important fringes of society for ages
- Put on openers — absurdly easy, pinching runs for ages
Buddy explains!
The straight part
We know that "long ago" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case long ago = donkeys years.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.