Actively loosen plums with glee for kid? (4,8,3)

I believe the answer is:

pull someones leg

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'kid?' is the definition.
(both can mean to joke or pretend)

I don't understand the rest of the clue.

(Other definitions for pull someones leg that I've seen before include "Kid" , "make member of relay team redundant?" .)

I've seen this clue in The Independent.

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