Voracious eater of filo custard slice (6)

I believe the answer is:

locust

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'voracious eater' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.

'of filo custard slice' is the wordplay.
'of' indicates a hidden word.
'LOCUST' is hidden in the letters of 'filo custard slice'.

Can you help me to learn more?

(Other definitions for locust that I've seen before include "Migratory crop stripper" , "Destroyer" , "Sort of migratory grasshopper" , "Destructive creature" , "Sturdy, resilient" .)

I've seen this clue in The Guardian.

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