They grow down from the torso (5)
I believe the answer is:
roots
'they grow down' is the definition.
The definition suggests an adverb but the answer is not.
'from the torso' is the wordplay.
'from' indicates an anagram (the anagram comes from the same letters).
'torso' with letters rearranged gives 'ROOTS'.
Can you help me to learn more?
(Other definitions for roots that I've seen before include "eg Parsnips" , "Sources, rummages" , "Origins; cheers (for)" , "Underground parts of plants" , "Underground parts of a plant" .)