The most common and most likely answer to this crossword clue is the 7 letter word QUARTAN
Q
U
A
R
T
A
N
Buddy explains!
The straight part
We know that "affliction which repeats" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case affliction which repeats = quartan.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 QUARTAN mean?
QUARTAN noun- A fever whose symptoms recur every four days.
- Recurring every four days; especially in designating a form of malaria with such symptoms.