Mashed potato's the stuff for dental hygiene (10)
I believe the answer is:
toothpaste
'stuff for dental hygiene' is the definition.
I can't tell whether this definition defines the answer.
'mashed potato's the' is the wordplay.
'mashed' indicates an anagram.
'potatos'+'the'='potatosthe'
'potatosthe' anagrammed gives 'TOOTHPASTE'.
Can you help me to learn more?
(Other definitions for toothpaste that I've seen before include "Stuff from tube" , "Cleaner used in bathroom" , "Cleaning item required" , "Dental cleaner" , "Dentifrice" .)