The most common and most likely answer to this crossword clue is the 6 letter word PIROGI
I've seen this crossword clue in The Guardian
P
I
R
O
G
I
Buddy explains!

The straight part
We know that "Polish dumplings (6)" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case polish dumplings (6) = pirogi.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 PIROGI mean?
PIROGI noun- A square- or crescent-shaped dumpling of unleavened dough, stuffed with sauerkraut, cheese, mashed potatoes, cabbage, onion, meat, or any combination of these, or with a fruit filling.
- A baked case of dough with a sweet or savoury filling, popular in Eastern Europe.