The most common and most likely answer to this crossword clue is the 8 letter word BIWEEKLY
I've seen this crossword clue in The Times
B
I
W
E
E
K
L
Y
Buddy explains!
The straight part
We know that "every fortnight" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case every fortnight = biweekly.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 BIWEEKLY mean?
BIWEEKLY noun- Something that is published or released once every two weeks.
- Occurring once every two weeks.
- Occurring twice a week (but see the Usage notes).
- Every two weeks.
- Twice a week (but see the Usage notes).