Outcast in force away to the west (5)

I believe the answer is:

leper

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'outcast' is the definition.
(I know that leper is a type of outcast)

I don't understand the rest of the clue.

(Other definitions for leper that I've seen before include "skin disease" , "Outcast, pariah" , "Social outcast" , "sick person" , "Undesirable" .)

I've seen this clue in The Sun.

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