The most common and most likely answer to this crossword clue is the 7 letter word TATTIES
I've seen this crossword clue in The Guardian
T
A
T
T
I
E
S
Buddy explains!
The straight part
We know that "Mash" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case mash = tatties.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 TATTIES mean?
TATTIES noun- Potato
- A woven mat or screen hung at a door or window and kept wet to moisten and cool the air as it enters.