A large stream of uninvited entrants (4)
I believe the answer is:
eden
'a large stream' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'of uninvited entrants' is the wordplay.
'of' indicates the answer is hidden within the clue.
'EDEN' is hidden within 'uninvited entrants'.
Can you help me to learn more?
(Other definitions for eden that I've seen before include "Old PM" , "Adam and Eve's garden" , "The perfect garden in need" , "Early garden - Cornish project" , "prime minister in the past" .)