Like a piper who got ratty when not paid (4)

I believe the answer is:

pied

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'like' is the definition.
Both the answer and definition are adjectives. Perhaps you can see a link between them that I don't see?

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

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(Other definitions for pied that I've seen before include "Foot over water [in]" , "featuring two colours" , "With patches coloured differently" , "Piper thus portrayed once" , "varying in colour" .)

I've seen this clue in the Evening Standard.

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