Onion ring found in the promised land (8)
I believe the answer is:
scallion
'onion' is the definition.
(scallion is a kind of onion)
'ring found in the promised land' is the wordplay.
'ring' becomes 'call' ('call' can be a synonym of 'ring').
'found in' is an insertion indicator.
'the promised land' becomes 'sion' (sion or zion).
'call' placed inside 'sion' is 'SCALLION'.
(Other definitions for scallion that I've seen before include "Vegetable" , "Spring 12" , "Green onion" , "A spring onion with long neck" , "sort of onion" .)