Pettishly spiteful? (5)

I believe the answer is:

catty

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'spiteful?' is the definition.
(I've seen this in other clues)

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for catty that I've seen before include "It's like a queen" , "Malicious" , "Bitchy as a feline" , "Spiteful in feline way" , "Mean and spiteful" .)

I've seen this clue in the Evening Standard.

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