Predatory type who's tasted blood? (5)

I believe the answer is:

leech

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'blood?' is the definition.
The definition and answer can be both people as well as being singular nouns.
Maybe they are linked in a way I don't understand?

I don't understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for leech that I've seen before include "Bloodsucking annelid" , "Blood-sucking worm or parasitical person" , "Freeloader" , "Blood sucker" , "Old medical attendant" .)

I've seen this clue in the Evening Standard.

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