The most common and most likely answer to this crossword clue is the 4 letter word YAMS
I've seen this crossword clue in Financial Times
Y
A
M
S
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The straight part
We know that "Roots" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case roots = yams.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 YAMS mean?
YAMS noun- Any climbing vine of the genus Dioscorea in the Eastern and Western hemispheres, usually cultivated.
- The edible, starchy, tuberous root of that plant, a tropical staple food.
- A sweet potato; a tuber from the species Ipomoea batatas.
- Potato.
- A oca; a tuber from the species Oxalis tuberosa.
- Taro.
- An orange-brown colour, like the flesh of the yam.
- (Cumberland) home