Herculean task for governing party (6)

I believe the answer is:

labour

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'party' is the definition.
(I know that Labour is a type of labor party)

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

Can you help me to learn more?

(Other definitions for labour that I've seen before include "21 [PARTY] ?" , "Left - work" , "Productive work" , "Donkey-work" , "Hard work, party" .)

I've seen this clue in The Times.

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