The most common and most likely answer to this crossword clue is the 5 letter word ROSTI
I've seen this crossword clue in The Times
R
O
S
T
I
More clues leading to the result ROSTI
- Bread filled with small fried potatoes
- Holy man in Republic of Ireland finding potato-based food
- Swiss dish acrostic contains
- Swiss dish — it's gold when turned over
- Swiss dish in bistro’s tip-top
- Onion originally included in stir-fried potato dish
- Dish of bistro’s tiramisu
- Dish served by prostitute
- Potato dish: it is served to men in retirement
- No introduction of butter in cooked bistro dish
Buddy explains!

The straight part
We know that "Swiss dish" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case swiss dish = rosti.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 ROSTI mean?
ROSTI noun- A traditional breakfast dish in Germanophone Switzerland (originally from Bern canton) made from potatoes, fried in a pan with butter or fat and widely varying other ingredients such as bacon, onions, cheese, apples or fresh herbs.