Beastly bit of polyglot terminology (5)

I believe the answer is:

otter

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'beastly bit' is the definition.
Although both the answer and definition are singular nouns, I can't understand how one could define the other.

'of polyglot terminology' is the wordplay.
'of' indicates a hidden word.
'OTTER' can be found hidden inside 'polyglot terminology'.

Can you help me to learn more?

(Other definitions for otter that I've seen before include "River-dwelling mammal" , "carnivore is concerned" , "Freshwater brown carnivore" , "River animal" , "Water creature" .)

I've seen this clue in the Evening Standard.

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