Long swimmers in river getting away from revelries (4)
I believe the answer is:
eels
'long swimmers' is the definition.
(I've seen this in another clue)
'river getting away from revelries' is the wordplay.
I cannot quite understand how this works, but
'from' could be 'e' (I've seen this in other clues) and 'e' is present in the answer.
The remaining letters 'els' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
'in' is the link.
Can you help me to learn more?
(Other definitions for eels that I've seen before include "They have long bodies and very small fins" , "Jellied --, traditional dish" , "Slender fish" , "Elongated fish" , "Fish (that may be jellied)" .)