Looking peevish in a servant's uniform (6)

I believe the answer is:

livery

I'm a little stuck... Click here to teach me more about this clue!

'servant's uniform' is the definition.
(I've seen this in another clue)

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

Can you help me to learn more?

(Other definitions for livery that I've seen before include "Distinctive uniform once worn by servants of posh people" , "Uniform -- suffering from gastric distress" , "group of servants" , "colours" , "Irritable" .)

I've seen this clue in the Sydney Morning Herald.

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