Endless source of nourishment (5)
I believe the answer is:
bagel
'nourishment' is the definition.
(bagel is a kind of nourishment)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for bagel that I've seen before include "It's edible" , "Ring-shaped bread roll" , "Doughnut-shaped bread roll" , "Toroidal bread roll" , "round fare" .)