Remove head from despicable person's fish (4)

I believe the answer is:

eels

I'm a little stuck... Click here to teach me more about this clue!

'fish' is the definition.
(I've seen this before)

I can't explain the remainder of the clue.

(Other definitions for eels that I've seen before include "Snakes wriggling in lees" , "They have long bodies and very small fins" , "Long, fleshy fish" , "Food for Cockney" , "Else they're fish" .)

I've seen this clue in The Telegraph.

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