Leafy herb stocks halve then plunge (6)
I believe the answer is:
endive
'leafy herb stocks' is the definition.
Although both the answer and definition are singular nouns, I don't understand how they can define each other.
'halve then plunge' is the wordplay.
'halve then' becomes 'en' (I can't justify this - if you can you should give a lot more credence to this answer).
'plunge' becomes 'dive' (synonyms).
'en'+'dive'='ENDIVE'
Can you help me to learn more?
(Other definitions for endive that I've seen before include "Envied (anag.)" , "Curly-leaved plant used as salad" , "Salad plant related to chicory" , "Envied the salad green badly" , "Edible plant" .)