Crossword Genius

Liberator freeing fifty as from thick treacle (5)

Ross

I believe the answer is:

moses

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

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

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(Other definitions for moses that I've seen before include "Hebrew leader and lawgiver" , "one found in bulrushes, too" , "One given tablets" , "Great Jewish leader who led the flight from Egypt" , "Mountain climber" .)

I've seen this clue in The Telegraph.
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