Cook without a root (4)
I believe the answer is:
stem
'root' is the definition.
(thesaurus)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for stem that I've seen before include "section of pipe" , "Ski turn and plant support" , "Originate (from)" , "supporter of tobacco?" , "Supporting structure" .)