Lively party, hit with cat (6)

I believe the answer is:

thrash

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

'lively party' is the definition.
'thrash' can be an answer for 'party' (thrash can informally mean a party). I am unsure of the 'lively' bit.

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

Can you help me to learn more?

(Other definitions for thrash that I've seen before include "Beat; party (colloq.)" , "Beat severely or defeat thoroughly" , "Hit hard" , "worst > party" , "tan" .)

I've seen this clue in The Guardian.

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