It tastes heavenly with ambrosia (6)
I believe the answer is:
nectar
'ambrosia' is the definition.
(synonyms)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for nectar that I've seen before include "Sweet fluid produced by flowers" , "Divine beverage" , "Fluid secreted by flowers" , "very nice drink" , "Sugary stuff in plants to attract insects" .)