Reaping hook, cruel, used by 50 English (6)

I believe the answer is:

sickle

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'reaping hook' is the definition.
(synonyms)

'cruel used by 50 english' is the wordplay.
'cruel' becomes 'sick' (I can't justify this - if you can you should believe this answer much more).
'used by' is a charade indicator (letters next to each other).
'50' becomes 'l' (Roman numeral).
'english' becomes 'e' (abbreviation).
'sick'+'l'+'e'='SICKLE'

Can you help me to learn more?

(Other definitions for sickle that I've seen before include "Farm implement" , "Harvesting implement" , "field-worker being a trimmer" , "Reaping implement" , "One stands for Communist" .)

I've seen this clue in The Sun.

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