Treats can be made from certain underground vegies (6)
I believe the answer is:
taters
'from certain underground vegies' is the definition.
I can't tell whether this defines the answer.
'treats can be' is the wordplay.
'can be' is an anagram indicator.
'treats' with letters rearranged gives 'TATERS'.
'made' acts as a link.
Can you help me to learn more?
(Other definitions for taters that I've seen before include "Potatoes (dialect)" , "starchy tubers" .)