One of the deliveries is eaten on break (7)
I believe the answer is:
neonate
'one of the deliveries' is the definition.
Although both the answer and definition are singular nouns, I cannot see how they can define each other.
'eaten on break' is the wordplay.
'break' is an anagram indicator.
'eaten'+'on'='eatenon'
'eatenon' anagrammed gives 'NEONATE'.
'is' acts as a link.
Can you help me to learn more?
(Other definitions for neonate that I've seen before include "Recent arrival" , "New baby" , "produced baby" , "very young child" , "Being recently created" .)