Caterpillar roll ingredient (3)
I believe the answer is:
'caterpillar roll ingredient' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for eel that I've seen before include "A sea snake" , "Slimy fish" , "Conger, e.g." , "Evasive type" , "slipper" .)