Beat victim one seizes and sucks (7)

I believe the answer is:

lamprey

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

'one seizes and sucks' is the definition.
I can't judge whether this defines the answer.

'beat victim' is the wordplay.
'beat' becomes 'lam' (I've seen this in other clues).
'victim' becomes 'prey' (prey is a kind of victim).
'lam'+'prey'='LAMPREY'

Can you help me to learn more?

(Other definitions for lamprey that I've seen before include "Eel-like animal" , "Freshwater eel-like fish" , "Eel-like creature - play REM (anag)" , "seafood" , "Marine carnivore" .)

I've seen this clue in The Guardian.

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