Good riddance to happy horsey worker (3)

I believe the answer is:

lad

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'worker' is the definition.
(I have seen 'Stable worker' mean 'lad' so perhaps 'worker' could also mean 'lad')

I can't explain the remainder of the clue.

Can you help me to learn more?

(Other definitions for lad that I've seen before include "Boy, young man" , "Young fellow" , "Chap, fellow" , "Son" , "Boy or youth" .)

I've seen this clue in The Sun.

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