The most common and most likely answer to this crossword clue is the 6 letter word NIGGLE
I've seen this crossword clue in The Daily Telegraph
N
I
G
G
L
E
More clues leading to the result NIGGLE
- Head of government in Scottish town backed complaint
- Horse in river finds carp
- Good to be in Scottish town, coming back for grouse
- Slight problem for horse, say, in river
- Worry, seeing gee-gee entering river
- Flipping short leg’s silly complaint
- Complaint, seeing two grand thrown into river
- Slight criticism of soldier over entering foggy glen
- Worry’s little good in Scottish town that’s been upset
- Complaint as girls drown in a river
Buddy explains!

The straight part
We know that "Worry," is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case worry, = niggle.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 NIGGLE mean?
NIGGLE noun- A minor complaint or problem.
- Small, cramped handwriting.
- To trifle with; to deceive; to mock.
- To use, spend, or do in a petty or trifling manner.
- To dwell too much on minor points or on trifling details.
- To fidget, fiddle, be restless.