Heavenly grub in bar: I am so excited! (8)
I believe the answer is:
ambrosia
'heavenly grub' is the definition.
The definition and answer can be both things that one consumes for nourishment as well as being singular nouns.
Perhaps there's an association between them I don't understand?
'bar i am so excited' is the wordplay.
'excited' is an anagram indicator.
'bar'+'i'+'am'+'so'='bariamso'
'bariamso' is an anagram of 'AMBROSIA'.
'in' is the link.
Can you help me to learn more?
(Other definitions for ambrosia that I've seen before include "food for Olympians" , "Gods' dinner?" , "Food and drink of gods" , "Siam boar as food for the gods" , "Wonderful food" .)