The most common and most likely answer to this crossword clue is the 6 letter word CRAMPS
I've seen this crossword clue in Independent
C
R
A
M
P
S
More clues leading to the result CRAMPS
Buddy explains!

The straight part
We know that "Periodic problem" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case periodic problem = cramps.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 CRAMPS mean?
CRAMPS noun- A painful contraction of a muscle which cannot be controlled.
- That which confines or contracts; a restraint; a shackle; a hindrance.
- A clamp for carpentry or masonry.
- A piece of wood having a curve corresponding to that of the upper part of the instep, on which the upper leather of a boot is stretched to give it the requisite shape.
- (of a muscle) To contract painfully and uncontrollably.
- To affect with cramps or spasms.
- To prohibit movement or expression of.
- To restrain to a specific physical position, as if with a cramp.
- To fasten or hold with, or as if with, a cramp iron.
- (by extension) To bind together; to unite.
- To form on a cramp.
- A cramping of muscles, especially in the abdomen or uterus.